I highly recommend the "algae free" maxi jet mod. Puts out 1600 gph with a very good flow pattern. Puts out more flow than a Koralia 4, and is smaller! That said, I also have two koralia 3's in my 75g, and am quite happy!
Strangerdejavu, do you just have the two koralia 3's in your 75g and nothing else? Its just that I have a 75g and am looking for new powerheads and have just seen your reply. I just wanted to check that the two are enough before I buy them.I highly recommend the "algae free" maxi jet mod. Puts out 1600 gph with a very good flow pattern. Puts out more flow than a Koralia 4, and is smaller! That said, I also have two koralia 3's in my 75g, and am quite happy!