I currently running 1300 GPH on a 50 gallon tank with a 3-4 inch sand bed. No problems but at first set-up, I had quite a bit of sand being blown around my tank. After the sand settled, everything was fine and the bottom of the tank looked neat, tons of little sand waves were made in the sand. If I change the direction of any of my powerheads, a big sandstorm will erupt but other than that, no problems. I dont mess with my powerheads, so I havent had a problem in a while. BUT, like I said, at first you will have a mess. Even my rocks were covered with sand and zoas dont like to be covered, neither do brain corals. My brain is fine but he slimed up when he first got covered with sand. The high flow helps with algae, I have never had an outbreak and I dont think that bad algae likes high flow. My substrate is white as can be without a hint of brown .... I couldnt imagine not having such a high flow. My corals also grow at a very fast rate, couldnt be happier.