I have 3 Hydor Koralia #1 powerheads for sale... The only reason that I want to sell them is so that I can get some #3's... I thought the 1's would be enough for my tank, and they are not... I have had them for about 4 days, and they are in perfect condition... These would be perfect for a 65 gallon or smaller... I would not use them if in anything larger than that, unless you are just looking for that extra little bit behind your rock work or something... These powerheads are awesome though, as they attach w/ magnets instead of suction cups... They swivel on a ball joint to direct them wherever you would like... very quiet, and energy efficient... and they also look very good in the tank