Replacing a UV Bulb vs Buying a New Clarifier
Replacing a pond UV bulb vs replacing the whole unit: bulb output decay, quartz sleeve fouling, cost and why UV stops working.
The short version
A UV bulb that still lights can be producing almost no useful output, because ultraviolet output falls long before the bulb fails. A fouled quartz sleeve blocks it entirely. Both are cheap fixes, and neither requires a new unit. Replace the bulb annually and clean the sleeve; replace the unit only if the housing leaks or the ballast fails.
At a glance
| 55W Replacement UV Bulb | Bio Balls for Ponds | |
|---|---|---|
| Restores UV output | Yes | No |
| Addresses nutrient load | No | Partly |
| Cost | Low | Low |
| Frequency | Annually | Rarely replaced |
| Common failure | Output decay, fouled sleeve | Rarely fails |
| Fixes green water | Yes | Indirectly |
Choose the 55W Replacement UV Bulb if…
Green water has returned and the UV is lit. Output falls well before the bulb dies, so a lamp that looks fine may be doing nothing. Note the fitting date, and clean the quartz sleeve at the same time, since a film of scale blocks UV even from a new bulb.
Check 55W Replacement UV Bulb on Amazon
Choose the Bio Balls for Ponds if…
UV manages the symptom. The nutrients feeding the algae come from fish waste and uneaten food, and biological capacity plus sensible feeding is what reduces them at source.
Check Bio Balls for Ponds on Amazon
We also have a full The Pond Guy UltraUV 18 watt review.
Related
Comparison based on published manufacturer specifications and the general consensus of owner reports. We have not tested these products side by side. Confirm current specifications and prices before buying. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you.
Frequently Asked Questions
How often should a UV bulb be replaced?
Typically annually in season, even though it still lights. Manufacturers rate output life rather than lamp life, and this is the most commonly missed pond maintenance item.
Why is my UV not clearing the water?
A tired bulb, a dirty quartz sleeve, or flow that is too fast for the unit's rating so water passes through without sufficient exposure. Check all three before assuming the unit has failed.
Does UV harm the biological filter?
No. Filter bacteria live on surfaces in the filter rather than floating past the lamp, which is why UV clears suspended algae without harming the nitrogen cycle.
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