I just brought an MP40wES for my 90 gallon yesterday. I had 3 Koralia's but still had dead spots and detritus buildup. After some fussing with trying to figure out what mode does what and how to set the mode, I got it going first on constant mode and immediately detritus starting coming off the rocks. Not bad. After more tinkering, I was able to set it on wave mode. I have a hammer coral on the other side of my tank and it is swaying. I don't have many corals due to a heater malfunction and presently I am trying to level out my parameters and trying to beat cyano so it is a lightly stocked tank when it comes to corals. So far, so good. It is quiet and gives the tank a clean look. I don't plan on having an sps dominated tank. Just maybe two or three. So one MP40 seems to be enough.....for now. Hehe.