The Wave 2k. I'll never go back to power heads again!!!!!!! I got mine six months ago or so. My corals thought they had died and gone to heaven. The unit is still in it's infancy, but the guy who invented it has a help number that comes with the unit. He has always been willing, and has solved the few problems I have had with mine. I wouldn't trade mine for anything.......well maybe a 500 gallon tank...giggle