Troubleshooting Guide for UV Sterilizers, Replacement UVC Bulbs/Lamps
Search AAP Supplies or Information
UV TROUBLESHOOTING, BALLAST, STARTER, STERILIZER OR OTHER BULB PROBLEMS If you need to replace your UV Sterilizer and want the best one that will last for over a decade, not a year or two, please watch this video: It is often difficult to tell the difference between a UV Bulb with a broken filament that was handled roughly during shipping or simply a defective bulb. The other aspect of "rough handling" can be from either (or both) the installer or the shipping service of the UV Sterilizer itself.
I've seen many times where a person was very aggressive in how they installed a UV or the Shipper (especially Economy UPS, FedEx, & USPS shipping services) will also "man handle", drop, etc. a package containing a UV Sterilizer. With the AAP/TMC UV Sterilizers that I've used and sold now for decades, this simply means pulling the contacts off the ends of the bulb/lamps and then reconnecting (often just pushing them in after being jarred will NOT make proper contact).
If you need to replace your UV Sterilizer and want the best one that will last for over a decade, not a year or two, please watch this video:
It is often difficult to tell the difference between a UV Bulb with a broken filament that was handled roughly during shipping or simply a defective bulb.
The other aspect of "rough handling" can be from either (or both) the installer or the shipping service of the UV Sterilizer itself.
I've seen many times where a person was very aggressive in how they installed a UV or the Shipper (especially Economy UPS, FedEx, & USPS shipping services) will also "man handle", drop, etc. a package containing a UV Sterilizer.
With the AAP/TMC UV Sterilizers that I've used and sold now for decades, this simply means pulling the contacts off the ends of the bulb/lamps and then reconnecting (often just pushing them in after being jarred will NOT make proper contact).
A bulb/lamp that blows the filament due to a short (such as caused by moisture) will have much more noticeable black scorch inside the quartz lamp near the blown filament.
In some cases, it is possible to "blow" a new bulb/lamp when an older bulb that requires much less energy to fire, does not "blow".
I have witnessed many new (& known working/pre-tested) lamps suffer a blown filament after blown filament, but an older bulb does not blow. The usual cause of this is a surge in voltage from the electronic ballast, which often does not damage a bulb with exhausted or low gasses.
The reason is, these newer hot cathode UV Bulbs take much more voltage to fire and if there is a short present your UV unit is either not giving the bulb enough voltage to fire, or during this high voltage start/firing, it can cause the new Bulb to "blow" (see Section #6 for further information).
So do not make that erroneous assumption that a blown filament when your older bulb works indicates a defective bulb, as although this can indicate a defective bulb, in my experience this is a poor test of whether a bulb is defective or not; Better to look at whether or not scorch marks are present on the UV lamp as this will tell whether it was/is a short or a defective bulb/lamp.
Some premium pond UV Sterilizers utilize fuses to prevent moisture damage from causing such an issue. Replacing this fuse is all that is needed instead of a much more expensive ballast replacement. See the Ballast section for more (including a picture)
Make sure the O Ring that seals the Quartz Sleeve is lubricated with Petroleum Jelly or Silicone Lubricant (preferred) prior to replacement.
If a leak is suspected or for simply better prevention of a future leak, removing this O Ring prior to inserting the Quartz Sleeve back into the unit and lubricating the O Ring is highly suggested. As well, for known cases of O Ring leaks, (with an O Ring Replacement is not readily available); carefully adding to windings/layers of Teflon Tape prior to reseating the O Ring has solved 80-90% of leaks for me.
If water flow is too slow or ceases all together, this can allow the lamp inside the UV to heat up to a point that blows the filament or simply damages the lamp where by it will not light (often leaving dark scorch marks if not blowing the filament).
This can also permanently damage an electronic ballast, especially if left 'on' after this failure.
With magnetic ballasts, this usually only damages the easily replaced starter.
An example of a cause of low or no water flow is a UV on a sump that has ceased functioning due to low water (often from evaporation)
Using a surge protector outlet can protect your UV Sterilizer and bulb/lamp. This said, the vast majority of "spikes" result in blown filaments, not simply non lighting or flashing bulbs.
However these switches can get bent or not depress properly, thus resulting in a UV bulb that either does not light or partially contacts to the light only part of the time.
This is easily detected by depressing the switch using a screw driver with the bulb inserted. The unit must be plugged in. (Make sure to shield your eyes/skin when testing and only test for a few seconds this way). If this is the problem, it can easily be corrected by bending the switch into a better position or tightening the switch (if this is an option)
Terminator Compact Ultraviolet Sterilizer, Clarifier for Aquarium, Pond
It's not uncommon to have a UV Bulb that is not inserted correctly, thus the new lamp will not light. The TMC UV Sterilizers and other T5 & T8 have lamp contacts that are easy to make the mistake of thinking the lamp is properly seated when it is not. Many compact UV Sterilizers also have contacts that are difficult to tell whether seated correctly or not.
This also can simply mean a defective or miss-matched UV bulb/lamp to the ballast
UV's use either electronic ballasts/transformers or magnetic ballasts/transformers. Electronic ballasts do not have starters and magnetic ones do.
If you have a magnetic ballast and your bulb is flashing, I would start by checking your starter as this is the cause of the problem in 80- 90% of flashing issues.
Some starters are good quality, and some are junk, and simply just fail prematurely. Sometimes these fail completely where nothing will happen with your UV lamp or sometimes partly where it cannot pre-heat a hot cathode UV-C lamp properly resulting in "flashing".
Flashing can also indicate that you simply have the wrong size starter or ballast, as there is not enough surge voltage to start the UV Lamp.
This is a relatively common problem when someone replaces a ballast or starter, especially since some starters and ballasts over-lap with HO lamps whereby a 20 watt HO lamp might require a 25 watt ballast & FS4 Starter (if a starter is required).
From my many years of experience, this is common with High Output (HO) UV Sterilizers such as the Aqua, Emperor, and TMC brands.
Also, if you have an electronic ballast and your bulb is flashing, I would check your connection first, bulb second, and ballast third. Be sure your contacts are properly seated onto your bulb, and all wires are connected properly.
Since most UV ballasts are electronic nowadays, the flashing may be the result of the ballast simply not having the correct "surge" voltage to light the UV-C Bulb, especially a hot cathode bulb/lamp.
It is also noteworthy that hot cathode low pressure mercury UV Bulbs are "aged" by each "start". So if your UV Sterilizer is on a timer with many cycles, this will often cause a bulb to fail in 1/2 to 1/3 of the time (depending upon start cycles). Flashing is common with a premature failure of this type.
Finally, if your ballast is electronic, I would test your ballast as per section #6, look for moisture as per section #2 (although a flashing bulb will NOT have a broken filament), or simply replace your UV Bulb.
Product Resource: Hot Cathode Low Pressure Mercury UV Bulbs
Starters like an electronic ballast can fail and in fact I once purchased a whole box of new FS2 starters that could not produce enough high-voltage electricity to light a single UV Bulb these were designed to light/ignite. However, unlike electronic ballasts, these are inexpensive to replace (in the case of my example, I simply returned these starters as defective).
Unfortunately there is no practical way to test a starter, however replacement of the starter is a simple and inexpensive problem to fix.
Failure of the starter is a common problem with magnetic ballasts (NOT electronic ballasts).
For instance the TMC 15 and 25 watt UV Sterilizer utilizes a FS-2 Starter, while the Fish Mate 8 Watt & 16 Watt (the 16 Watt is a pair of 8 watt T5 Straight tube UV-C Lamps) utilizes the FS-5 Starter.
*TMC Pond Advantage 15 & 25 Watt UVs
*TMC Vecton 15 & 25 Watt UVs
*Fish Mate 8 Watt G8T5, PUVLB508 UV Bulbs
Here is a rough guide of Starters versus wattage:
A common sign is a UV lamp that will just glow at the filament but not fully light.
It takes more energy to fire a new high intensity hot cathode UV bulb/lamp than an old lamp or a low intensity cold cathode UV Bulb. By low intensity, these UV Bulbs only produce a fraction (less than 15%) of the necessary UVC.
It is noteworthy that not all original equipment UV Bulbs are not high intensity UV Bulbs.
This is a more common problem than many realize based on our 40+ years experience.
This problem generally occurs with electronic ballasts, not as often with the magnetic ballasts that require a starter, however a starter (which is inexpensive to replace) can also fail to produce the voltage to fire a new hot cathode, low pressure UV Bulb while firing an older "broken in" bulb.
As well it is also not uncommon for a weak ballast to fully fire one new UVC lamp and not another.
Often when this "phenomenon" of an older lamp lighting when a newer UV Bulb/Lamp will not light, involves an older bulb that is well past its useful life.
It takes very little energy to light a 2-3 year old UV-C Bulb. Your UV bulb should be changed every 6 months for optimum performance or every year for minimum performance (or in cooler climate ponds). This phenomenon is much less common with bulbs changed within proper intervals.
What is also noteworthy is with many electronic ballasts, their "surge" voltage goes downhill slowly. So often an electronic ballast that is producing 90% of the optimum surge voltage may even light one hot cathode high output bulb and not another, even from the same manufacturer due to variances in the bulbs themselves. I have observed this many times over the years.
See the section in this article under UV Sterilizer Maintenance (3/4 through the article) for tips on testing your ballast:
It's also noteworthy that even then an electronic ballast may have the correct normal operating voltage, but cannot correctly pre-heat a hot cathode UV Bulb (this is not a problem with magnetic ballasts, assuming a functioning starter).
This is because to fire the gas in fluorescent hot cathode UV-C lamps, electrical voltage often exceeds 500V, and can exceed a Multi Meters limitation for testing. Usually when testing a properly functioning electronic ballast (or starter for a magnetic ballast), my Multi-Meter will 'beep' out around 350 volts as per this important surge voltage where as a improperly functioning ballast will not display this surge, only the normal operating low voltage.
In fact this inability to "surge" in voltage is a very common electronic ballast failure, regardless of brand! For this reason sometimes a ballast (or starter) with a slightly lower than adequate surge voltage may light a new hot cathode bulb, but not another, this is a phenomenom I have observed many times over the years of my servicing UV Sterilizers.
This is not a fool proof test. Sometimes simply taking a new and known "working" lamp and placing it in the fixture with the ballast in question is the most accurate way to test (please note that it must be a NEW UVC lamp/bulb, otherwise this method is not accurate at all).
First, let me point out that magnetic ballasts rarely fail, often lasting more than a decade. In 100% of magnetic ballasts failures that were under a decade in age in my extensive years of experience were because the ballast was damaged. Usually this damage was extensive moisture/water damage
Second, let me quote Honeywell's website (for UV air purifiers):
"Note running a burnt-out bulb may burn-out the ballast"
The facts are you can and often will damage your electronic ballast beyond the ability to light a new hot cathode UV Bulb (Honeywell uses hot cathode UV bulbs as original equipment).
Third, Some Premium UV Sterilizers utilize fuses to prevent electrical damage from power surges, moisture, etc.
With these, all that needs to be replaced is the fuse.
In fact in my considerable experience using UV Sterilizers, in particular with pond applications, the fuse was all that needed replacing. An example is the AAP/TMC 110 Watt Pond Pro Advantage UV.
Product Resource: TMC 110 UV Fuse & Other Parts
Forth, Do NOT run a High Output UV Sterilizer via a controller such as an Apex. These can limit voltage needed for the surge in start up. This is especially true with UVs that utilize electronic ballasts, which can be permanently damaged by such use.
A surge protector or other multi outlet is generally OK, but not a controller.
Finally, if your electronic ballast has failed (& you are reasonably "DIY handy"), you can often find a common magnetic ballast to replace your electronic ballast. Just make sure that any replacement magnetic ballast has a rating within +/- 10% of the wattage of your UV Bulb (do not forget to purchase the correct starter for your magnetic ballast too).
Do not make the false assumption you MUST replace your electronic ballast with the exact ballast supplied by your manufacturers UV Sterilizer; An electronic ballast can also be replaced with another manufacturers electronic ballast. As long as the rated lamp service falls within your UV-C bulbs wattage.
This said, as I noted in the "Flashing" section of this article, many high output UV lamps such as those meant for Aqua & Emperor UVs require a slightly higher surge voltage.
This means, as an example that often the next size up ballast and/or starter is required such as a 20-30 watt ballast instead of a 14-20 ballast for a 15 Watt Aqua Lamp.
If unsure, it might be best to purchase an original equipment ballast. During my years in aquarium/pond maintenance where UV Sterilizer use and repair was a specialty, I often had the luxury of multiple ballasts on hand, so if one did not work, I would try the next size up, but the average user may not have this luxury or the time to go back and forth to their electrical supply store.
As well, do NOT assume that if your ballast will light one UV Bulb and not another, that the problem is the bulb.
A ballast that will not light a hot cathode bulb may simply not be putting out the high voltage surge to light the hot cathode lamp.
It takes almost nothing to light a cold cathode bulb.
Keeping an inferior or weak ballast to light an inferior UV bulb will only result in very little true UV Sterilization and thus raises the question of "why even keep your UV Sterilizer when it will perform almost no level one UV Sterilization?"
In the end, often when it comes down to a bad ballast, especially with the more "throw away" Chinese UVs where parts are not always available, you likely will save both time and especially hassle simply replacing the entire UV Sterilizer!!
As a side note, if you purchased your UV Bulb here, it can be returned for full credit toward a better UV Sterilizer (85% otherwise)
After a meeting with one of our sister maintenance companies in LA, he noted that of the dozens of Coralife Turbo Twist UVs, he has now had 100% failure with their ballasts over the last few years which includes replacing many to only result in failures again.
If you are having trouble with your UVC lamp/bulb in ANY Coralife UV, I strongly recommend replacing your ballast or better simply replacing the UV with a better design such as the TMC Vecton Advantage UV!
Product Resource: TMC Aquarium and Pond Premium Ultraviolet Sterilizers
Put another way, I've seen many a case where someone has replaced just one lamp and not both and the UV Sterilizer will not light. It is important to ALWAYS replace ALL lamps/bulbs in such units (in some cases the client assumed the lamps were good, but were damaged by an electrical surge, and had me out to replace the ballast, when all that was needed was changing both lamps).
In fact, our UV Hot Cathode Germicidal UV Bulbs are superior to what many consider to be the leaders in UV-C Lamps/Bulbs with a higher output, however because of the high energy gasses these UVC replacement lights often take a few minutes to warm up upon the first firing which sometimes makes persons consider the light defective, however this is simply typical of this type of high output hot cathode UV-C low-pressure mercury arc lamps!
| TMC UV Sterilizer | Compact- UV -Sterilizer | UVC Replacement Lamp | T5-T8-UV-Bulbs | UV-Bulb-TroubleShooting | Quartz-Sleeve-Ballast | Internal UV Sterilizer | Pocket-Purifier | 15 Watt UV Sterilizer |
U.V. Sterilizers | Filters | Pumps | Fish Food | Aquarium-treatments | miscellaneous2 | Lights-Heaters | Aquarium-Decorations |
| Return Home | Aquarium_Information | Aquarium Products | Downloads | FAQ | Other | Contact Us | View Cart |