Sponge filtration is an often overlooked type of filtration for both large and small freshwater tanks and bowls, and even ponds or marine aquariums. Many aquarists look past these filters because of their simplicity, but therein lies their quality.
I have used these filters for my aquarium maintenance business for 32 plus years with excellent results in freshwater, saltwater and ponds. (The picture to the left is a Hydro Sponge #1 in a 6 x 6 x 6 Betta tank.)
The best sponge filters (such as the Patented Hydro Sponge Filters) can be used to compliment another filter, such as a power "hang on back" (HOB) or canister filter, or even as a stand alone filter, as per our extensive controlled tests. We found that only fluidized sand bed filters out perform sponge filters for aerobic bio filtration.
In fact I, and many other aquarium professionals, have used sponge filters as the only source of aquarium filtration.
With this in mind, people purchasing one of the many 'Aquarium Kits' sold at Walmart and elsewhere would be much better off with a superior bio-filtration such as our Sponge Filter Kit instead.
As a bio filter, most premium sponge filters (such as our Premium Hydro Sponge Filter) are vastly superior to Under Gravel Filters as per extensive controlled tests performed by us in the 1990s.
This is due to the very porous nature of a sponge filter that allows for extensive colonization of nitrifying bacteria, assuming your aquarium or pond is adequately circulated.
Please note that many sponge filters and even patent infringing "knock offs" made by a variety of brands (such as Lees, Tetra, Hagen, SF-XY, XY-380, AquaTop) are NOT made of the same patented sponge material as ATI's patented Hydro sponges. Thus these do not perform nitrification at the same level, as my tests confirmed in the 1990s, often by a LARGE margin due to a much more porous design that simply traps more debris and allows more bacterial colonization.
As well, these patented sponges have a micro design that does not collapse on itself as readily as other designs. Please read further for a more in depth explanation of this.
These lower end sponge filters also degrade much quicker, as many users can attest to.
In fact in tests using the XY-380 commonly sold via Amazon, using very similar bio load aquariums, I found the amount of organic debris during the same time period to be almost double for the patented AAP Hydro Sponge Filter, thus demonstrating a MUCH higher capacity!!
The bottom line is there is a reason for the patent and why ATI is constantly legally battling these knock offs for patent infringement when they try to improve.
A couple of the reasons for better test results when compared to an under gravel filter, is that a well designed sponge filter does not have “dead” spots, nor do sponge filters trap decomposing organic mulm in pockets, such as is the case with under gravel filter plates (which can lower KH/pH, increase nitrates, and even promote Aeromonas or Saprolegnia pathogens!)
In addition, these tests showed that these filters were also superior to most popular power (HOB) filters for bio filtration (such as the Marineland Bio Wheel).
Bio Wheels are touted for their ability to host beneficial nitrifying bacteria and yet, this simple sponge filter outperformed them.
Some Positives & Negatives of Quality Sponge Filters:
Quality Sponge filters are a much better choice for bio filtration for planted aquariums over popular canister or HOB filters as they strip less CO2.
Only a fluidized sand bed filter exceeds the sponge filter for aerobic bio filtration without as much CO2 stripping for planted aquariums.
A lack of CO2 is one of the limiting factors in a planted tank so it is a huge advantage to have more available for your plants to utilize for photosynthesis!
Quality Sponge filters are the clear choice for shrimp aquariums, especially where shrimp are breeding.
The reason is that you can get a much more gentle current, when the filter sponge is mated with an air pump and diffuser.
More importantly, there is no way a baby shrimp can get sucked into the filter as they can with most other filters. The only safer option would be an under gravel filter, but this is a poor choice for other reasons.
Quality Sponge Filters are probably the best choice for Betta bowls or tanks due to their bio efficiency, lack of turbidity, and low risk of fin damage.
Sponge Filters are also the filter of choice among breeders (including use in their display aquariums), especially high value discus breeders.
In both cases, this is because of the safety they provide to the fish as well as their huge capacity for biological filtration which results in fantastic water quality that is so important for discus as well as other achieving viable fry.
Even for large aquariums, sponge filters, such as the Hydro Sponge #5 PRO (or even Hydro Pond #2 for even larger aquariums/sm. ponds), often provide superior biological filtration when compared to popular HOB filters such as the Aqua Clear 70.
This is not to say the AC 70 is a bad filter, either. It is not. Nonetheless, my controlled tests showed that sponge filters were capable of much higher biological filtration than even a good filter like the Aqua Clear!.
With some HOB Filters, such as the Penguin Bio Wheel filter, the results of our controlled biological filtration tests were even more dramatically in favor of sponge filters. (For example, I conducted tests with a Penguin 170 vs. a Hydro Sponge #3 in getting these results.)
Although many aquariums keepers are convinced that many wet/dry and canister filters are the "be-all, end-all" for aerobic bio filtration, this is NOT the case. When we used canister filters in our tests, we found otherwise, especially when compared to larger sponge filters such as the Hydro Pond models (which are often used for large aquariums or aquarium wet/dry systems).
When one considers the simplicity of a sponge filter over most canister filters, this is a "no-brainer" for savvy aquarium keepers that find canister filters too cumbersome!
As noted earlier, only a fluidized sand bed filter outperforms a Hydro Sponge Filter for aerobic bio filtration. In fact, some fluidized sand bed filters outperform even the most pricey canister filters such as the Fluval FX5 for aerobic bio filtration!
When you consider cost, simplicity of set up, and maintenance with its capacity for filtration, a sponge filter is clearly something to seriously consider in your aquarium build.
Sponge filters are also available as pre-filters. Using a sponge pre-filter extends the time between cartridge changes in power (HOB) filters, slows the accumulation of organic debris buildup inside a canister filter, and prevents fish fry from being sucked up the intake tubes of the filters.
More importantly, a sponge pre-filter can add some very essential bio filtration redundancy to often woefully inadequate HOB filters that frequently lose much of their bio capacity with each filter change.
Sponge filters do perform mechanical filtration (removal of debris from the water column), however this is not where they excel (although certain brands definitely perform much better than others).
Biological filtration is their strength, which is why the best filtration would be a combination of a sponge filter and a HOB (power filter) such as the more premium Rena Smart or SuperClean Filter or SunSun Value HOB Filters.
These would provide a great combination, a one-two punch!
When a separate sponge filter is employed with an aquarium power filter, canister filter, etc, this improves redundancy of filtration in the case of one filter failing or accidentally being "over-cleaned" (where beneficial bio filtering bacteria are destroyed).
Back to mechanical filtration, this is where the use of patented sponge filters can make a difference. I have run Lees, Tetra, as well as many of the cheap Chinese brand Sponge Filters (such as the poor quality Jardin) and found poor "pick-up" of organic debris even next to the sponge filter, then switched to the AAP Hydro Sponge Filter with the same exact air pump and this was no longer a problem.
Even with the Hydro-Sponge Filter, placement of the filter, air or water pumps size and even simple extension of the air line deeper into the filter can improve pick up of larger organic debris.
See the "Use (Air Pump or Power Head Methods)" Section of this article for more.
The only aspect of aquarium/pond filtration where the sponge filter falls short is in chemical filtration.
This can be added with the use of activated charcoal, or other adsorbent. However, even if the sponge filter is the only means of filtration, it should be noted that most established/healthy aquariums do not need constant chemical filtration. This is especially true in the case of planted tanks.
As well, the aquarium keeper could place a nylon bag with Nirox Superior Grade Carbon, SeaChem Purigen, or other chemical filter media at the base of the sponge filter and the movement of water around/through the sponge filter will allow for some chemical filtration.
The picture to the left demonstrates the use of a prescription bottle for a DIY carbon filter. This can be placed under or behind a sponge filter where the water current is stronger. I have found this to be very useful in tanks where the sponge filter is the primary filter in a small aquarium such as a Betta tank.
In this picture API's AmmoCarb is being used.
There are a couple other options for aquarium keepers that can negate the need for chemical filtration. One is the good old fashioned method of simply performing regular water changes. Or, the addition of a power (HOB) filter such as the SunSun HBL-501/701.
Either of these filters would allow you to use chemical filtration and would provide a good compliment to your sponge filter. Even though water changes will likely still be necessary, power (HOB) filters could lengthen the time period between them.
Another more obvious negative reason against the use of sponge filters is a question of pure aesthetics.
While the ATI Sponge Filters are, pound for pound, just about the best aerobic nitrifying bio filters you can buy, many people do not like the looks of them.
Despite the clear benefits to these filters, there is still an ugly sponge in your aquarium. Rather than seeing this as an obstacle, some consider it a creative challenge.
Many aquarium keepers simply use rocks, plants and/or other décor to hide these sponge filters or pre-filters. Or, a black/dark background on your tank can also help the sponge be less noticeable. For many breeders, fish farms, and the like, the negative aesthetic aspect of the sponge filter is easily overridden by their inexpensive high biological filtration capacities.
Let's get back to the positive attributes of sponge filters and their applications. Often, aquarium filter kits that are made up of quality sponge filters along with air pumps or power heads are superior to many of the aquarium kits that are sold in the bigger pet stores.
These are the "starter kits" that come with a small tank and are often very basic aquarium power filters, or even basic corner filters (or similar) with little bio filtration capacity. Beginning aquarists would be better served to consider a simple power head and sponge filter in their first tanks!
This is especially true of big box department store or chain pet store kits that rarely have the bio capacity of a sponge filter kit such as one that utilizes an ATI Hydro Sponge. Simplified maintenance along with superior bio filtration capabilities would equal greater chances of success for beginning fish keepers.
"The sponge filtration was inspired by Carl more than 2 years ago when I started into the hobby. Since then, I have progressed to using sponge filtration as the only filtration in my 210 gallon planted freshwater tank. The seeded sponges were used when combining 5 fish tanks into one tank.
Two weeks later, I am enjoying my aquarium.
My fish include a 2 yr old scat fish( was in fresh water at lfs), 8 Bolivian rams( just laid eggs again), 2 German rams( new male in the pair), 5 angels( have laid eggs, no fry), 7 adult dollar fish ( 2 yrs old) and 5 juveniles), a 2yr old dinosaur bischer, 30 cardinals and assorted neon tetras, 1 cory(left), 1 curviceps,4 platys(had fry).
I discarded the canister filter, biowheel filter, and use sponge filtration exclusively. Thank you for diligent,intelligent, and thoughtful sharing of your knowledge."
Jacqueline A., Florida
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Here are some Basics about Aquarium Sponge Filtration; How Sponge Filter Work:
Sponge filters work by having aquarium water drawn through the porous sponge material in which debris from the water column is trapped mechanically.
At this time, aerobic bacteria living in the pores feed on nitrogenous wastes such as ammonia and nitrites that are suspended in the water.
Water is pulled through the sponge media via a lift/vacuum caused by air bubbles from an air pump attached to the filter via air line tubing or by a power head attached to the top of the lift tube.
Simply put, a sponge filter uses a water pump to pull, or push, water through the pores in the sponge or an air pump to create a suction that does similar.
As the water passes through the pores of the sponge, they trap debris of varying sizes. It can then be rinsed or squeezed out (see more on this in the maintenance section) during cleaning. These pores have a a considerable amount of surface area where aerobic bacteria can propagate and exist.
The size and quality of the pores will determine flow rate, how much debris can be trapped, and how large the bacterial colonies will be that can exist within the filter. This means that knock off sponge filters that are of poor design will have very little internal space, collapse quickly, and allow poor internal flow. You might save money but you will get less for your money and be replacing the sponge and/or filter sooner.
With sponge pre-filters, the concept is similar. Water is drawn through the sponge media by the suction of the filter such as a HOB, power head, water pump, or canister's motor unit. The same actions take place. Debris is trapped and nitrogenous wastes are consumed by aerobic bacteria.
The type of sponge material can affect both mechanical and biological filtration. This is where many of the cheap knock offs, or even name brand sponge filters such as the Lees sponge filter, do not perform as well. Not all sponge materials are created equal! These utilize pores that are too fine and are made with a foam material that is too dense resulting in poor flow, clogging, and a far less than desirable biological function.
A good test of the quality of the sponge material is when you go to rinse/clean the sponge. Upon removal, the patented AAP Hydro Sponge filter along with all others will likely drip some of the trapped "yuk" from your aquarium while removing if you are not careful due to material trapped just at the surface.
However upon rinsing in a bowl or small bucket of used aquarium water, one will often find it does not take nearly as many squeezings to clear most every sponge made as when compared to the Hydro sponges which will often take 2 or 3 buckets of clean rinse water to clear since these sponges trap/hold so much more!!!
The picture to the above shows the two types of patented sponges made by ATI/AAP HydroSponge where the pore density is obvious and quite different from just about any other sponge filter available.
The patented reticulated "PRO" sponges are for higher flow and more coarse particulates. While the standard patented sponges are for lower flow, but smaller particulates.
As noted, this material as per my test has far more bio/mechanical capacity than any of the cheap foam sponge material used in most common and Chinese knock offs. As even the DIY or similar products using poret foam (such as used by SwissTropicals) still does not match capacity as per my use/tests.
Back to flow, the reverse situation can be a problem with certain reticulated sponges when used in the wrong flow environment. Although the ATI Hydro Sponge is the best in sponge filters, their patented reticulated sponge material is best used in higher flow rate environments instead of their patented standard sponges.
Examples of ATI Reticulated sponges are the Filter Max #3, PRO, and Pond sponges. While the basic design of the filters remains the same, the design of the sponge differs allowing for higher flow environments, as well as more coarse filtration.
As an example, I do NOT recommend the Hydro Sponge PRO Filters in small sizes such as the #2.
While the #5 PRO is an excellent filter for the environment and flow rates for which they were designed, we have found that the Hydro Sponge #2 & #3 PRO do not work as well in both the flow rates, typical particulates in the water column, and the bacterial loads found in the smaller tanks that for which a #2 is designed.
Thus, in the end, the #2 Standard sponge out-performed the #2 PRO in a smaller tank (10-20 gallons). So, it is critical that the sponge material be suited to the flow called for by the tank size, fish size, and bio load.
As another example, I have run aquariums with just one Hydro Sponge #2 using the PRO (Filter Max #3) sponge (making this a #2 PRO Sponge Filter) with a common mixed community tank. While this is an excellent sponge for higher flow rates, especially mated to a Filter Max #3 Pre-filter, it performed poorly in clearing debris and murky water.
HOWEVER, within hours of changing out with a seeded standard Hydro Sponge #2 filter, the tank was clear.
So if "fine" filtration is needed, the standard patented sponge from ATI is best (& actually has a higher capacity). Where as if higher flow rates are needed and fine filtration is not as important, the patented reticulated sponge filter is best.
You could also combine filtration types (coarse & fine) by using a Hydro Sponge #5 PRO with a #5 Stackable attached (which is a standard sponge). Using a Hydro Pond #2 or #4 and replacing one of the reticulated sponges provided with a standard #5 would also work.
It is noteworthy that water will always flow in the path of least resistance, so this combination method with not draw nearly as much water through the fine sponge as the coarse reticulated sponge.
The picture to the left shows a solution for larger aquariums in need of higher flow filters, but still desiring good fine mechanical filtration that will not impede overall flow.
This is a Hydro Sponge 5 Combo which combines the patented ATI 5 Pro and 5 Standard. This can be used with either a power head or air pump and will easily work in aquariums 60 gallons or larger (or smaller if need be). This filter will also easily out perform both mechanically more importantly, biologically most all Hand on the Back filters including the larger Aqua Clears. Make sure when rinsing, that the fine standard sponge is always on the top for optimum effectiveness since water will always follow the path of least resistance and using the PRO reticulated sponge on top will not allow much water flow through the fine sponge.
Seeding the sponge media biologically:
To “seed” the sponge media you can use the sponge from an established aquarium or leave a sponge in the water column of an established aquarium. This can be sped up by placing the Sponge Filter directly in contact with other established filter media or moving gravel around the Sponge Filter. The reason is that nitrifying bacteria are not found in high numbers in the water column (open water), however gravel and even more so other filter media are like to have these bacteria in VASTLY higher numbers.
The use a of a Stackable Sponge Filter (pictured to the upper left) in an established aquarium can then provide a second (or 3rd if 3 are "stacked") sponge for seeding another aquarium you may be starting (or exchanging with a friend or local aquarium store).
Another un-related advantage of a stackable sponge filter is that these create a space for fry to hide in breeding tanks and also allow for expanding your filter to fit expanded bio loads, especially for larger aquariums or breeding tank systems.
You also can simply place the filter in your aquarium and allow the sponge filter media to establish itself biologically. There are many other methods that work well, some are discussed here:
Reference: "The Aquarium Nitrogen Cycle"
If you would like more information on sponge material, please see the following article: Sponge Media Material
FURTHER SPONGE FILTRATION INFORMATION
How a Sponge Filter Works/Functions
(Air Pump or Power Head Methods):
When your Sponge Filter is attached to an air pump, the rising column of air bubbles in the tube pulls water with it. The bubbles rise because they are buoyant and the water is pulled along behind them. A larger diameter lift tube allows for a higher flow rate (this is where Hydro Sponge filters excel).
You can measure the water flow (which can be useful to know) by slightly tilting the filter with the top of the outflow just above the aquarium water line and timing the fill rate into a pitcher or gallon jug. If it fills the jug in 30 seconds, you multiply 2 times per minute times 60 or 120 gallons per hour.
You can also add an air stone or air diffuser to the end of your tubing in the outflow tube to produce more bubbles and more lift.
Click on picture to the left to enlarge
How to Determine Water Flow when an Air Pump is Used to Power your Sponge Filter:
Most air pumps are rated in liters per minute (or cc) of air volume. In experiments we have carried out, with no added head pressure via lifting above the water level, you can achieve an equal amount of water moved.
By adding an air diffuser such as those sold by Hydro Sponge (separately), the surface area of the bubbles increases greatly and actually doubles the water volume moved!
Example: if you employ a 3 liter per minute air pump along with an air diffuser, you will achieve 6 liters of water per minute, which divided by 3.785 (liters in a gallon), you get 1.59 gallons per minute or 95 gallons per hour
As per "Freshwater Aquarium Basics: Filters", it is best to have between 3-5x the water volume of the aquarium in turnover (depending upon the type of fish/aquarium kept). So, for a 50 gallon aquarium, the filter in this example moving 95 gallons per hour would fall slightly short of the ideal. This means another sponge filter, power head, or even a simple air bar is required for proper water movement and filtration in this example.
The air pump method is generally the better choice for these reasons:
For use in a hospital tank
For a breeder tank or fry rearing tank
Any tank where the fish prefer a more quiet flow such as Discus or Bettas
For simplicity of set up for the aquarium keeper (e.g. beginners)
Sponge Filter/Air Pump Combinations Suggestions:
Please note that these suggestions are far from an exhaustive list, so matching similar sponge filters and similar air pumps should yield similar results (although it is noteworthy that there are no equals to the patented Hydro sponge filter, even though most air pumps are quite similar in quality and design).
*Hydro Sponge #1 or #2: SunSun YT-301 or Million Air 80. For a bit more power, the Million Air 200 or Fusion 300. *Hydro Sponge #3, #4, or #5: Million Air 200, Fusion 300 which have more depth abilities than the MA80 and other smaller single outlet pumps. The Million Air 400 or 600 and the Fusion 600 or 700 can be used with an airline 'T' to combine each outlet for extra deep tanks such as over 24 inches. *TWO Sponge Filters: Million Air 300/400, Fusion 600 or Fusion 700 for deep tanks. *FOUR to SIX Sponge Filters: Fusion 700, (an air line control kit is suggested for more than 2 per air pump outlet).
As a note for those employing an air pump to power their Sponge Filter;
Almost all air pumps use some variation of vibration technology whereby a magnet is moved back and forth via the alternating electrical current to then operate a diaphragm and thus produce air.
This inherently is not quiet, no matter what someone might otherwise try to tell you.
Some air pumps such as the Fusion have a baffle system that helps, but it still does not get rid of all noise (the Fusion would be your best choice if you are very noise sensitive, but it still is not perfect).
A bigger difference between some of the cheaper Walmart brands and even the SunSun YT versus the Million Air, Fusion and some other better models is the rubber armature and other parts such as the diaphragm are not thick enough or of poor quality rubber. This results in a pump that get much more noisy over time and much more quickly than the better quality pumps due to the rubber stretching/degrading/tearing. However as per initial noise, often the cheapest air pumps are no noisier out of the box.
If noise is an issue, make sure your pump is not on a hard surface where it can vibrate, also for better "noise protection", placing your pump in a small box wrapped in old socks or similar has worked for me with my clients who are sensitive to noise.
In the end though, even a power head makes a slight rattling noise. As well you will have the sound of splashing or gurgling water, so as I have told some of my aquarium maintenance clients over the years, if you cannot handle certain noises, do NOT place ANY aquarium where this may bother you or someone else that is noise sensitive!!!
When attached to a power head, the pump pulls the water thru the sponge.
With this method I recommend using an air diffuser that generally comes with most power heads to improve dissolved oxygen levels (unless used in a planted freshwater aquarium).
Even if you cannot, or choose not, to use an air diffuser (not all power heads have this feature), you can still aerate the aquarium through breaking the water's “surface tension” using either any directional control that your power head has, or by placing the Power head (pump) outlet near the surface so as to cause ripples on the surface.
With a power head, you will not see any bubbles flowing up the lift tube as with an air pump. However, with both methods there is a rising column of water through this tube that in turn is pulling water through the sponge filter material.
The Hydro Sponge #5 can handle flows up to 400 gph (depending on bio load), if a higher flow is required, the Hydro Pond Filter #2 or #4 can also be used in an aquarium (I have often used the Hydro Pond #4 as a pre-filter for high gph pumps in wet dry sumps).
The Hydro Pond #4 is pump driven and can handle flows up to 1500 gph.
Hydro Pond #2 is air driven and can handle flows up to 1000 gph. And of course the Hydro Pond Filters can be used in ponds where they are excellent complimentary filters or even stand alone filters (usually in low bio load ponds).
The power head method is generally the better choice for these reasons:
Higher flow rates are desired
Cross current is necessary, especially for long tanks
Generally larger fish that are more “destructive”, Although I still recommend protecting the sponge filter/ power head set up from these fish (such as many Cichlids) by leaning large rocks next to the sponge filter and power head to keep them in place.
Marine Reef applications
Please see this short video highlighting the differences between an air pump powered sponge filter or a power-head powered sponge filter:
The picture to the left shows a simple suggested large aquarium set up using a Hydro Pond #4 Filter (a Hydro Sponge #5 would work well too) and the differences in flow using either air pump or a power head.
In addition, please note the suggested rock placement you can use to keep the filters from being knocked over if large fish, such as Oscars, are present.
With both air pump or power head methods, the water is pulled through the sponge filter media where debris is mechanically trapped and aerobic bacteria remove nitrogenous waste such as ammonia and nitrites.
For ponds, a more porous sponge media is better to allow a better flow rate and less accumulation of small debris from mechanical filtration that might easily clog a more 'fine to medium' sponge.
For aquariums with internal, pre-filter, or standard sponge filters, a medium porous sponge material with many tiny pores to trap bacteria is best (again this is where the Hydro Sponge Filter excels with its patented design).
With a new sponge filter, your filter primarily operates mechanically (trapping debris in the sponge which can be rinsed/squeezed out in de-chlorinated water), while the more important bio feature of utilizing nitrifying bacteria to remove toxic ammonia & nitrites takes 4-8 weeks to be fully functional. This can vary due to the age of the aquarium or new tank cycling methods. Please see this excellent article for further information on this subject:
*I should note: from my experience, even though a power head may move more water, I prefer connecting sponge filters to air pumps over water pumps as I find this application to be more simple, less messy, and having less problems with fish knocking power heads off the lift tubes. Your experience may vary but this is what I have found.
When deciding on how high the lift tube should go (whether air driven or pump driven), consider the flow pattern you would like to achieve in your aquarium. I recommend as large a pattern as possible. Therefore, I cut the lift tubes (easily done with a hacksaw) as close to the water surface as will allow for evaporation and other minor changes in tank level and remain submerged.
With some very small tanks (such as Betta tanks), I run these sponge filters on air power and I do not use the clear lift tube at all. Instead, I only attach the air diffuser to the bulls-eye of the sponge filter.
Even when air powered, the air lifts the water through the filter to the top of the lift tube where the water then exits, however, the air bubbles will continue to the surface. The picture to the left (click to enlarge) shows these differences.
For tall/deep aquariums; the use of lift tube extensions can be used to provide a better flow pattern.
The Hydro-Lift can be used with the 1 inch high flow outlets found on the Hydro Sponge Filter. In addition, these lifts work for both air-driven or water-driven applications.
Generally, the use of lift tube extensions can be an advantage for flow patterns, but not always, especially if upper level HOB filters are used. A deep aquarium would be just fine with short lift tube combined with a "hang-on-the-back" power filter providing upper circulation. However if the sponge filters are your primary source of filtration, I would suggest the use of lift tube extensions for deep aquariums.
If other filters are present, such as a "hang-on power filter," then, generally your best results will be achieved by placing the sponge filter on one side and the hang-on power filter, or other filter, on the other side (such as the return from a canister filter).
Since hang-on power filters have a water fall effect, these have less horizontal water movement, so in tanks over 36 inches in length the use of a power head on your sponge filter is suggested for better horizontal circulation.
For tanks under 24 inches in length, generally the air pump method will achieve a good circulation pattern.
If power heads or related circulation pumps are already present (such as those on many internal filters too), the use of a air pump driven sponge filter with its superior vertical circulation would generally be most complementary.
If you desire less agitation when using an air pump to power your sponge filter, I recommend cutting the top of the lift tube as close to the surface as possible. I also recommend using an optional air diffuser with your sponge filter which will produce a smaller bubble than a sponge filter used without a diffuser, thus resulting in less agitation of the water. Please note that air diffusers are sold separately with most brands of Sponge Filters.
If further agitation reduction is desired/required (especially with small fish bowls), the use of air line control valves of valve kits can be used (a valve kit can be used to bleed off excess air pressure).
Air Pump Attachment
*Diagram for sponge filter with an air pump installation (click to enlarge):
Note that even without the use of the optional diffuser, I have attached a small piece of tubing to the underside of the bulls-eye (frame #4). This is IMPORTANT as it allows the column of air to draw water upward deeper into the sponge filter, thus providing better more thorough filtration and better uptake of debris from the water column in the aquarium.
This next picture displays a cut away view of a Hydro Pond #2 Filter, showing connection to an air line for use with an air pump.
Outside of this being a double sponge with two bulls eyes instead of one as per standard Hydro Sponge Filters, the internal design is the same for all sponge filters when used with air driven power.
This filter is excellent for both large aquarium use or Patio Pond use (such as container ponds)
Power Head Water Pump Attachment:
These two pictures show sponge filters set up with basic power head pumps such as the newer generation SunSun JP-23 pictured here (similar to many other older generation basic power heads such as the Marineland, Maxi-Jet or AquaClear).
To snug the fit even more, often the use of Teflon Tape or even a thin ribbon of Duct Tape wrapped around the top of the power head intake strainer will make for a more snug fit.
I should also note that, while these diagrams shows a secure fitting for many aquariums from my experience, for large fish (such as adult South American Cichlids), I would suggest using heavy rocks to brace the sponge filter & power head as these fish will often knock the power head off the lift tube.
As the reader can see, the power head can be mounted directly on the Sponge Filter or on the lift tube and each have their advantages:
Lift Tube Mounting Advantages include better over all circulation, especially in taller tanks.
Direct Sponge Filter Mounting advantages include better stability and less chance of fish disrupting the pump from the filter. As well generally a better fit for aquariums under 12 inches in height
Please Click on the pictures to enlarge for a better view
Readers should note that many power heads including the one pictured include a nipple on the outlet nozzle; this is for attaching an air intake diffuser tube which is little more than an air line tube that draws in air for futher aeration of the aquarium via the water current exiting the power head water pump.
In most instances these will not work if the pump is much more than a few inches below the water surface. It is also noteworthy that these small air line rubes often get build ups of hard water that need t be rodded out with a paper clip or similar DIY tool so as to allow free flow of air.
The picture to the left displays how to utilize a Hydro Sponge #2 to make a Mini Hydro Sponge for use in small bowls (such as 1 quart, 1 liter) or small 1-2 gallon aquariums where the Hydro Sponge 1 is not desired.
The beauty of this idea is that, not only do you get a nice compact Sponge Filter, but you get a spare sponge too at no extra cost!
As already noted earlier, Hydro Sponge Stackables can be used to add additional filtration in breeding tanks and also to provide safe areas to hide for fish babies (fry).
The use of these sponges, especially the Hydro Sponge 5 Stackable also allows for expansion with larger tanks, often with surpassed bio efficiency and ease of maintenance over frequently over-touted canister or wet-dry filters.
As well, when a #5 stackable is added to a #5 PRO filter, this will provide different levels of mechanical filtration (as well as flow rates), which further increases the viability of the sponge filters to be the primary aquarium filter. Please click on the picture to the left for an example.
Although mechanical filtration is not the main strength of a sponge filter, it can still remove copious amounts of debris from the water column when properly connected.
If not properly connected, you will see little, if any, mechanical filtration and even biological filtration will suffer.
The picture to the left (Please click to enlarge) shows water flow through a sponge filter depending upon air diffuser, airline tubing, and lift tube placement.
As you can see, a sponge filter with no lift tube and with no extension of tubing (or air diffuser) has a poor flow through the sponge material (if any flow at all).
The reason is that the air bubbles rising in the column will create a vacuum. However, if there is no lift tube (or very little), no vacuum is produced and the water will simply flow upward with the current of water, mostly avoiding the sponge (which will have more resistance).
The point is to overcome the resistance of the sponge material with a stronger vacuum produced in the lift tube. Additionally, an extension of airline tubing into the sponge filter and/or the use of an air diffuser or air stone can extend this vacuum deeper into the sponge filter, thus providing a better flow.
When new, sponge filters have a tendency to float. Air will remain trapped inside the sponge pores. You can correct this with several squeezes of the sponge. You should be able to clear most of the fine air bubbles that can cause floating.
Over time, nitrifying aerobic bacteria (& other organics) will add weight to the sponge that will make the it much heavier. Thus, sponge filter floating will be less of an issue.
However, some lower quality sponge filters such as the Lees or Tetra, tend to trap more fine air bubbles. They also have poorly weighted bases (if any). Floating can be a major issue for these cheaper fliters that requires placing a rock or similar weight on top of them to deal with this problem.
*Not Trapping Debris:
This is likely caused by incorrect installation so that air or water flow is not properly pulling debris into the sponge, please review the pictures throughout this article for correct set-up/installation.
Clogged or full sponge filter material will also not allow proper flow. An aged sponge filter or poor quality sponge material (which is common) will also clog much more quickly, especially as it ages. See also the Media Care Section
Sponge media that is also not cleaned often enough, is set up incorrectly, or is of low quality will also have a chance of releasing debris back into the aquarium when cleaning.
If this is a problem, I would suggest vacuuming around the filter prior to the removal/disconnection of the sponge filter from the air pump or water pump. Then I suggest changing the sponge, checking installation, and/or improving/upgrading your sponge filter.
Finally with many cheap Sponge filters that have become common of late, these are simply not that porous and simply cannot trap much when compared to the patented AAP/Hydro Sponge Filters. Back To Top
UV STERILIZER SPONGE FILTER APPLICATIONS
Although not a common application, it is possible to connect a sponge filter to a UV sterilizer (unlike a hang on the back aquarium power filter).
In fact this makes a relatively easy way to utilize the benefits of UV Sterilization in an aquarium that either has a sponge filter or a HOB filter and do you not want to spend more money for a filter that connects easily to UV sterilizers.
The addition of a sponge filter with a UV sterilizer to an aquarium with an existing filter (such as an Aqua Clear, Penguin, etc.) will also improve bio filtration, mechanical filtration and insure redundancy that insures against the failure of the primary filter.
See these pictures (click to enlarge).
*The first shows a ReSun King 1A Pump connected horizontally to a Hydro Sponge #3 Filter. You will note the use of Teflon tape or vinyl tape to make a more solid connection. One inch vinyl tubing can also be used between the pump and lift tubing. The Rio 1000 or many other pumps can work. You could also use the Via Aqua 480 with the slimmer Hydro Sponge #2 filter).
*The second shows a Via Aqua 480 or SunSun JP-23 Power Head also connected to a Hydro Sponge #3 Filter mounted vertically.
Other ideas would include a larger Hydro Pond #4 connected to a higher flow pump, such as a Rio 1700 Pump for a larger tank such as a 100 gallon aquarium.
With the first two examples, a Terminator 5 Watt UV or the TMC Vecton Premium 8 Watt UV sterilizer will work.
With a higher flow rate (such as a Rio 1700 or similar pump), consider a Terminator 18 watt, TMC 15 Watt Vecton, or a 25 Watt Vecton UV Sterilizer.
Finally, another alternative is a UV sterilizer that has a large reticulated sponge filter built in.
From my testing and use of many UV sterilizers, the best of the bunch in terms of filter capacity and, more importantly one of only a handful that can actually perform level one sterilization, is the SunSun CUP Series UV/Filter.
Besides the more common stand alone sponge filter, the sponge pre-filter is also a viable sponge filtration option. These are especially useful in preserving viable nitrifying bacterial colonies in HOB filters during changes of filter media, especially with cartridge filters that don't have other means of maintaining bacteria., as many of these filters lack bio media chambers
This is especially true with economy HOB power filters sold at Walmart, PetSmart, etc. such as the Top Fin & Aqua-Tech HOB Filter.
This is a common problem with beginner aquarium keepers that have single cartridge filters, in that every time they dispose of a filter cartridge, they throw away the majority of their viable aerobic nitrifying bacterial colonies, resulting in toxic ammonia spikes!
Sponge pre-filters such as the Filter Max can be attached to the intake of most canister or aquarium power (HOB) filters.
In fact the use of premium sponge pre-filters such as the AAP Filter Max can cut down on the need to change filter cartridges in power HOB filters by 200-300%, saving money, and time.
This is especially effective for high efficiency power filters such as the Rena Smart Filter which tend to clog faster than some aquarium HOB filters.
Besides extending the length of time between filter cartridge changing in an HOB power Filter, as with other good sponge filters, these pre-filters will increase bio capacity of your over all aquarium filtration.
As well these pre-filters, whether connected to a HOB filter or canister filter will also prevent young fish fry from being sucked into an intake as is often the case with canister filters and many HOB filters as well.
The only drawbacks are that your filter must have a cylindrical intake tube (which rules out some Marineland filters) and that you do not achieve the filter redundancy in the same way as having a separate Sponge Filter.
However these Sponge Pre Filters also add protection for fish getting trapped against the intake strainer or literally “sucked up” as with fish fry (babies).
The type of sponge material also affects the flow rate, as the AAP Filter Max #3 uses a patented reticulated sponge material that only traps larger debris and clogs much slower, while the Filter Max #1 and #2 have the original ATI Sponge material that traps smaller debris, but also does not allow as much current and clogs more quickly.
The Filter Max II/III combination provides both aspects of these patented aquarium sponge filers. This filter combination is provided with a lower flow, but higher fine debris mechanical #2 sponge along with the higher flow rate reticulated #3 sponge.
This is a great idea for higher flow filters where more fine mechanical filtration is desired, but would clog up too fast under normal use with the standard Filter Max II.
Another use of Sponge Filters is as a basic Pond Filter or using a Hydro Pond Sponge Filter as an excellent and efficient large flow pre-filters in aquarium sumps for both salt and freshwater aquarium systems.
See the picture to the left as an example which also includes a Filter Max over the intake to the sump.
These same Hydro Spond Filter that are designed for small pond use also make excellent high capacity bio filters for large aquariums.
Whether it be the double reticulated air driven #2 Hydro Pond or the water driven #3 (single) or #4 (double), these high capacity sponge filter can be the PRIMARY filters for aquariums as large as 250 or even larger in multiples or as the secondary filter!
Pictured are a water driven #3 to the left with a Rio 20HF pump and an air driven #2 to the right
This picture to the left shows a Hydro Pond #3 attached to a Rio 1000, 1100, or 1700 (the Hydro Pond #4 fits the same)
Many, if not most, internal/submersible filters are essentially sponge filters that are self-powered sponge filters.
These have the advantage of being easy to tuck up high in an aquarium corner more out of the way than a standard sponge filter.
Also, with the SunSun HJ-752 Filter pictured here you can cut the sponge in half to allow more room, and then add other filter media such as carbon or Matrix. However, a small bag, or other means of blocking the carbon from being ingested into the motor, should be used.
Some of these filters also have multiple chambers where other filter media can be placed (example the SunSun HJ-952 (210 gph)).
The disadvantage, especially when compared to the patented Hydro Sponge filter line is their sponge bio capacity is much lower based on the size and efficiency of the sponge material.
The sponges (foam inserts) found in filters such as the Aqua Clear Filter also qualify as a sponge too. But they are not sponge filters in the classic sense.
These “foam inserts” do NOT have nearly the same pore capacity as comparably sized Hydro Sponge Filters. Care and use should be considered the same for this type of sponge inserts.
One little “trick” I like to do with these sponge inserts is to cut them in half or even thirds so as to “seed” multiple sponges for use in helping jump start the nitrogen cycle in other tanks or as back ups to other tanks under treatment.
The main problem with sponge filter media of any type is clogging due to mechanical filtration.
The better designed sponge filter medium is one that maximizes the amount of time between cleanings. These sponge media will not clog under normal use. This, of course, will vary even by the same manufacturer due to what the sponge filter media was designed for.
For instance a Filter Max #2 is a fine sponge media that traps smaller debris and will thus clog more quickly in a tank with a high bio-load than a Filter Max #3, often requiring more frequent rinses in de-chlorinated water.
Unfortunately the many cheap sponge filters flooding the market via eBay, Amazon, & other discounters has but a fraction of the capacity, both bio and mechanical.
When the flow slows or water begins to flow around the sponge media (such as in many Aqua Clear Filters), you need to rinse/clean your sponge filter media.
The best method is to collect used aquarium water in a bucket from a water change and squeeze the sponge several times until nothing more is expelled from the sponge. This water is then disposed of and new water can be added to the aquarium to replace the water used for sponge cleaning.
You also may use de-chlorinated tap water or well water (without added chemicals) for rinsing your sponge media. I often will use both methods and I will use the de-chlorinated tap water for the final rinses until the rinse water is no longer dirty.
The reason to rinse with used tank water or de-chlorinated tap or well water is so you DON'T destroy beneficial aerobic bacterial colonies that form in the pores of the sponge media over time. The chlorine in the water would kill the bacteria and cause an ammonia spike.
To prevent too much dirty water returning to the aquarium when removing a sponge filter, sponge pre-filter, etc., I suggest having a small container to catch the water that might pour back as soon as the sponge is removed above the water line.
If a large amount of "gunk" returning to the water still is a problem when disconnecting for maintenance; my suggestion is to change your sponge more often and/or move up to a larger size sponge.
This said, based on considerable experience using many different sponge filters over the years in literally 1000s of aquarium applications, with the best designed & patented sponges, what little "gunk" does fall back into the aquarium is but a very small fraction of what you will often rinse out. Often the AAP Hydro sponge will require multiple rinses before the water is mostly clear due to the high bio and mechanical filter capacity.
With ATI/AAP sponge Filters and Filter Max, all sponges are interchangeable, so as an example you can easily add a Hydro Sponge #3 sponge to a Hydro Sponge #2 frame (the exceptions being the Mini, #1 Filters, and the #1 Filter Max).
Depending upon your aquarium (or pond) bio-load, as well as the pore size of your sponge material, the frequency of rinses can vary.
Generally a well “mated” sponge filter, or other filter that employs a sponge, assuming some quality, will need to be rinsed every two weeks. Although once per week or as long as once per month are not unusual either. Often in aquariums or ponds with multiple filters, the frequency of rinses is less due to the redundancy of filtration, which is what I recommend.
Often as the sponge material ages from use, it will clog quicker too and again lessor quality sponge material will also break down more quicker than the better patented sponge material.
When your sponge media starts to degrade or does not “spring” back from rinsing, the sponge needs to be changed. Generally this can be anywhere from 6 months to 3 years.
It is best to add an additional sponge to your aquarium ahead of time to allow this sponge to “seed” with aerobic bacteria.
This can be achieved by simply placing the new sponge in an area of high water flow and high dissolved oxygen or adding a second sponge filter, pre filter, HOB filter, etc. in your aquarium and allowing the sponge media to “seed”. The time I generally allow is from 14-21 days for proper bacterial “seeding”.
Simple to use: most run on very basic air pumps or power heads. One of the best beginner aquarist filters due to simplicity and cost. But, sponge filters are also popular with breeders and research facilities, since they are very efficient yet simple filters. They can be used as the primary filter EVEN for large aquariums with sponge filters such as the Hydro Sponge #5 PRO.
Excellent biological filtration: they are very porous and can maintain very large aerobic bacterial colonies in proportion to the space they occupy.
Easily the filter of choice for hospital aquariums/tanks (i.e. tanks for sick or injured fish).
In hospital aquariums, sponge filters will NOT remove medications like filters that contain chemical media such as carbon.
Sponge filters also allow for bare bottom tanks eliminating the problems of potentially disease harboring and sometimes medication absorbing sand/gravel in hospital/breeding tanks (some gravels will absorb chemical treatments such as copper, Methylene blue, Malachite green).
Also, sponge filters will not “suck” weak fish into filter intakes as many others can.
Mechanical filtration: although they are not the best mechanical filters, they still do a good job for their small size and make excellent secondary or primary filters when used in combination with other filters such as HOB, canister, or internal filters.
This said the Patented Hydro Sponge Filter has a much higher capacity than any of the popular "cheap" knock offs or DIY sponge Filters. The patented reticulated Hydro Sponge PROs or Pond filters are designed for much higher flow rates with a lower frequency to clean for a given volume of water and debris run through these over time, but these also do not trap as fine of debris as the standard Hydro Sponge Filter.
Those who say sponge filters need too frequent of cleanings are likely either not using the correct Hydro Sponge filter for the job at hand or are using a cheap knock off or DIY sponge filter.
Very few “dead” areas trapping pockets of noxious bacteria, unlike under gravel filters and even wet/dry filters (of which, in my experience, many are overrated). Quality sponge filters are also superior to overrated Bio wheels for bio filtration as per my own tests performed at many of my multiple aquarium clients.
Simple to clean: just remove the sponge and squeeze or rinse in old aquarium water or de-chlorinated tap water. The advantage here is that the aquarist is less likely to ignore cleaning the filter (unlike many complex filters), which can lead to organic build up, increasing nitrates and lowering KH and ph.
Sponge filters are great in Marine aquariums in a few of different ways:
One way is in a sump using a Hydro Pond Filter IV, or similar, attached to a high flow pump as a pre-filter (this is a very efficient application!), or with a small power head pump run separately in the sump as a bio filter.
The other (usually in a reef application) is inside the aquarium with either an air pump or power head. The beauty of either application is they are simple to rinse out with used aquarium water. In the reef application this was especially useful in that I could dispose of a lot of debris before it cycled and produced nitrates. They are an excellent compliment to “live rock” filtered reef aquariums.
Sponge filters used in reef aquariums are easily rinsed which keeps them from becoming the so-called “nitrate factories” that many other mechanical/ bio filters can become. Canister filters or even bio balls can be much more difficult to quickly and frequently rinse and have a tendency to build up nitrates in the reef tank.
Sponge filters or sponge pre-filters (including the Hydro Pond IV) work great in conjunction with the Berlin Filter method due to their ease of cleaning and simplicity of set up.
I have used them here as additional in-tank filters for Nano Reefs, pre-filters before entering a sump, or very often inside the sump of refugiums or mud filters attached to the pump for added bio/mechanical filtration (make sure to rinse every week for maximum efficiency and for low nitrates.
The ease of rinsing is why sponge filters are useful for this application. However, if the aquarium keeper ignores regular cleaning of the sponge, the sponge filter will fail in this application as it too can become a nitrate factory if not rinsed.
Probably the best choice of filtration for delicate Discus or Angel tanks due to the fact that they do not attract noxious bacteria when used in a bare bottom tank.
Easily the best filter for a Betta housed in a small tank or bowl. Bettas, with their long fins, can get caught on intakes of HOB or other filters. They excel over UGF in bowls or small tanks in that they are easier to maintain, do not attract noxious bacteria, and are more efficient biologically and mechanically.
They are great for cichlid breeding, as they are not easily disturbed by cichlids' tendency to dig.
Inexpensive and cost effective.
Now available in larger sizes for aquariums over 60 gallons or ponds.
These sponge filters are a great compliment to canister or HOB filters.
Sponge filters can even be used in ponds.
With the Hydro Pond Filter, simply attach a power head pump (such as a Rio 1700 or Rio HF), then run your return line wherever you like (waterfall, etc.), or the Hydro Pond II can be run off a simple air pump. These filters can work on ponds up to 1500 gallons (or more with additional units).
These Hydro Pond Filters (the #4 in particular) also work well in large aquariums or in the sumps of large filtration systems, especially when you need flows in excess of 400 gph.
There also are sponge filters that are used as a pre-filter for intakes of canister, wet/dry, power filters and more.
They offer increased bio-filtration to your existing system, as well as protection for baby fish, plants, or anemones from being sucked into the intake of your existing filter.
It is also important to note, that not all sponge pre-filters are the same (including the Hydro sponges). A Filter Max #1 is NOT going to allow the efficient use of a filter such as a Whisper 30, where as a Filter Max #3 with the higher flow, more porous sponge will.
It should also be noted that the Hydro Pond Filter #4 can be used as a pre-filter in large aquariums as well and actually improves filtration on many canister filters, especially micron filters such as a Magnum (they also decrease frequency of cleaning and mulm build-up within canister filters).
These pre-filter sponges are especially useful for HOB (power filters) as they increase their bio capacity (far more than bio wheels in experiments I have done) and retain the aerobic bio filtering bacteria during filter media changes.
Without these sponge pre-filters, many HOB filters are poor to fair bio filters.
Sponge filters are great for planted aquariums: they do not interfere with root structures and maintain a biological balance that is ideal for planted aquariums.
Only a Fluidized Sand Filter is superior for planted aquariums
Sponge internal filters or a pre filter attached to a power head are great for powering UV Sterilizers in small aquariums or Nano Reefs.
They are also useful for acting as a pre-filter for the often incorrectly underrated yet superior fluidized sand filters.
Bio Wheels and Wet Dry filters are superior to sponge filters. -MYTH
In theory the added oxygen of bio wheels and wet dry filters is great.
But in reality, the channeling of wet dry filters and the deposit build up of Bio Wheels lowers the bacteria surface area. Besides, it's not really necessary. The dissolved oxygen already present in your aquarium is more than sufficient to maintain healthy bacteria colonies. Compare a wet dry filter to a marine tank with live rock and other means of mechanical filtration and you will find the live rock is superior even though it is under water.
All sponge filters are the same and only for small aquariums. –MYTH
The flow design, sponge media material, and sponge size all are important. A large sponge filter with sponge media of a high and proper sized pore count is an extremely efficient filter.
Compare the sponge design of the patented Hydro Sponge to a cheaper Lees, AquaTop, Hagen (Elite), or Tetra sponge and it is obvious. These cheaper sponges clog faster and do not have the pore density of Hydro Sponge filters.
My controlled tests in the 1990s showed comparably sized ATI/AAP Hydro Sponge Filters had a higher bio capacity to ALL others.
In fact, in tests comparing the Hydro Sponge #5 PRO with Aqua Clear 70 and 110 HOB filters, the Hydro Sponge #5 beat the Aqua Clear 70 and was at least as good as a Aqua Clear 110 (these HOB filter utilize sponge inserts).
For the price the Hydro Sponge #5 PRO is the clear winner compared to both. Unfortunately the aquarium hobby is full of anecdotal information knocking sponge filters as low tech, out dated, too small, etc. which is all not true when truly objective comparisons are made.
Some history as per my professional use of the ATI/AAP Hydro Sponge Filter:
As noted earlier I performed controlled tests in the 1990s using these filters with use dating back to the 1970s.
However after selling off the LFS part of my business due to a move to Oregon to protect my family, I ceased selling these filters as I no longer had a resource for the filter. So when I re-started my business online and as per my still running aquarium maintenance company (but now operated by another), I gave the Chinese made SF-XY a try as it looked very similar to the Hydro Sponge.
Interestingly while very similar to the patented Hydro Sponge Filter, and while they performed well, they did not perform as well.
Then later a representative from ATI contacted me about patent infringement by the SF-XY Sponge filter and I then re-established contact and sales with this company.
The point being is many companies have tried to copy these filters, but even then have failed even while infringing upon patent rights. WHY? Simply because these are superior to all other sponge filters (including DIY), and by a wide margin.
This use now numbers in the 1000s, many of which includes controlled tests where I have tested these sponges under all sorts of conditions such as different bio loads, after drying the sponge out and then using, with different sponge media types, even with different product runs where the filters varied slightly or were of a different color; and I know extensively what these filters can and cannot do in an aquarium, sump, pond, etc.!!
Finally, it is also noteworthy that an undersized sponge filter (including a Hydro Sponge or Filter Max) will work no better than an undersized filter of any other type, especially when not cared for regularly.
Sponge pre-filters lower the efficiency of power filters or canister filters- MYTH
This is true only if you attach a low flow dense-pore sponge filter to a higher flow power filter or use one of the “cheapie” brands available. A sponge pre-filter may not be for everyone, but they do have their place and with proper installation can actually improve filtration. The pre-filtration of larger debris and prevention of baby fish being trapped are specific benefits.
Hydro Sponge Review from Renee (goldenpuon) from “Everything Aquatic”
"I thought I'd write a review of the Hydro Sponge filters I purchased from Carl a while back. The results are excellent too.
Better than any sponge filter I've ever owned. It picks up fish waste very well and now I have to do less than half the cleaning for my tank. I had a guppy tank I was cleaning every two days with a micro filter installed. Now all I have to do is clean it every 1 1/2 weeks!
The Hydro Sponge also creates a good amount of water disturbance with very few bubbles produced making it a great for providing oxygen for fish. Its quality is just as good, if not better than most power filters out there. It is also small and doesn't take up much space while providing a great place for beneficial bacteria to grow. This makes it much more useful than really any other filter for tanks with high ammonia, nitrites, and nitrates. It is also much less expensive than filters that require carbon.
All you have to do is replace the sponge every 6 months and it costs little more than a dollar while carbons in power filter must be changed at least every month each costs a few dollars. One of the best filters I've ever owned, I highly recommend it for aquariums of all sizes!
Hope you guys like my review. I'm not just pointing out the positives here, they really are true."
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