Roger, I currently have two 6100's on a multi controller in my 260 gallon....I am converting this tank to FOWLR, and tieing a 50 gallon reef tank into my system......Other time constraints have made me desire a smaller tank for the reef, as I can get my hands in easier, and keep up with maintenance easier etc. Plus the Family has a desire to try some Larger Aggresive species in a big tank......Now onto the question, I plan on the reef being bare bottom, is it feasable to run both the 6100's, Dialed down and pulsing in this tank, or would I get more than enough flow out of one, and just leave the other in the big tank for extra flow?