I too would like to know that for my 46gal tank. As of now I'm using a Red Sea Prizm skimmer HOB, says for a tank up to 100gal I believe.. got it for 50bucks so couldnt resist. So far it's doing a good job. I don't really have a big bio load so maybe that's why. But, I plan on getting more fish later on and not sure it will be enough. And was wondering if there is a better HOB one.