At one point I had a problem with ich, I had an adult Emperor Angel and a Bluethroat Trigger infected, I was prepared to throw anything I could think of at it to help them get rid of it, Cupramine in the QT, garlic, and of course the UV. I ended up losing the battle with ich and lost my two fish, I kept the UV running to help kill free floating parasites. I have never rid the tank of ich 100%, my Cleaner Wrasse keeps that in check, so obviously the UV doesn't completely rid the tank of parasites although I'm sure it helps. I couldn't run it fallow for a few months because I would need a very large QT which I don't have. The rest of the fish are good though. My other tank has never had ich, and until I run into it I don't see the need. As far as algae goes, I don't see any difference in the tank with vs the one without. I think high nutrients and lighting have the biggest impact on algae and introducing fish without quarantine is probably the biggest cause of ich, UV or not.

Thx everyone. I think with everyones insight I'm not going to run one. I have a good skimmer so I'll stick with that for now. Thx everyone.

I was considering running a UV sterilizer when I was doing research on my backyard pond because everyone said you have to run one if you want clear water. I found a company out of the States who said otherwise. What happens when the water is passed through the system? Sure it will kill all the nasty stuff that causes algea and other things but it also kills your beneficial bacteria. Not worth the extra cost, just my 2 cents.

IME, if you have a reef UV will provide no measureable benefit. Claims UV units will reduce algae...well that is misleading, because it will not help with that (despite what the big box store may tell you). Chances are if you used one for 3 months you would see not difference in your tank and want your money back. I was sold one back in the day before I knew better, I recently chucked it.

If you have a fish only tank UV can be quite useful AT controling waterborne parasites if a properly sized unit with proper flow is used.

good with parasites like ich,but a uv sterilizer shoud be put on a timer for 3-4 hours a day depending on the size of the bulb in comparison to your size of tank!algae blooms are a cause of alot of things not done right in your tank, best to see where you went wrong or what you're missing
over feeding,cycling,skimmer,filtration,husbandry,light ing,temperature,live stock etc....................

this is just my insight on a salt water set up! not much of an idea on a pond set up!!