Hi Deb. I understand that UV isn't needed for treating ick since fish can naturally get rid of it on its own. But are you saying that the Ick stayed on the fish just as long even with your 25W UV running? I would have expected that the more powerful UV would reduce the number of days that the fish will have ick. That would be the benefit.

As for slime algae, yeah, it would have to go through the sterilizer in order to kill it.

So I think its fair to say that its useful for tanks with problems (like mine) and not useful for healthy tanks like yours.

I have the 36W turbo twist and what a waste of money for my 170 gal tank. ick or no ick it doenst kill crap in the tank. it never worked for me. ozone will be the next treat for the tank.

Yes I use one but am unclear as to it's effectiveness.

Greg, has your rate of STN decreased since putting it back on?

Yes. I was using a small 8w "LifeGuard" unit on my 35 gal Q tank (the units sold by Pentair Aquatics). It was given to me - so the price was right! :lol: To pump the water through it, I hooked it up inline with a small Fluval canister filter. The Fluval was on its last legs so the flow rate was very, very slow. How much of an impact it had is difficult to say. I did have one fish go through Q with ich that cleared up, but I used a variety of approaches - in addition to the UV. I've since taken it out as I replaced the Fluval with a Magnum and am not sure if I will put the UV back in-line.

I think UV system are beneficial for reducing infectious agents - in particular bacteria and infectious stages of Ich and similar protozoans. If I had a serious outbreak in my main display, I would seriously consider the use of UV as a part of a strategy to beat the parasite back where copper would not be an option. However, they are not fool proof and effectiveness depends on many factors alluded to by others (wattage of bulbs, age of bulbs (aka intensity), flow rate (aka contact time). It's not surprising that many large commercial aquaculture operations use them effeectivel to manage disease (or more correctly, to reduce the infectious burden on their fish).