UV sterilizer....how long to see results?

[newfound77951]

So I have a very, very bad case of green water in my planted 55 gal. I have a borrowed 9W UV sterilizer that I just got a bulb for last night. I don't have a canister filter so I jury-rigged a small powerhead (250 liters/hour or about 1 tank volume per hour) to the UV. As of this AM it had been on for ~12 hours with no visible difference in the tank. How long should it take before I see a change? Also, there is no way to tell if the darn thing is even on; we have a big UV here at work and you can see the purple light out the end but I can't with the little one....not sure if I'm supposed to or not, don't really want to take it apart and look with it on (ouch). Advice??

 

[QTOFFER]

The UV should irreparably damage the algae's DNA and kill it within hours. It won't physically remove the dead algae, however, and neither will your filter. Do a big water change and keep the UV on. The algae won't grow back, and after a few water changes, the water will be clear.

 

[CompMage]

Do to currents in your tank, it may take some time before you really get to all the water in your tank. I would move the intake around every now and then to make sure you're getting as much as you can.

But pending how the sterilizer is setup you may not be able to see the light. The one I used once was setup so you could not look in it. Box said it was a safty feature. But it worked.

You need to be doing extra water changes, twice a day if you can. Dead algae is very harmful to your fish and can cause an ammonia spike as it starts to decay.