I think you can dial down if you don't need max flow now and you can dial up once you need it in the future; how your rockscaping, what corals you keep and density of your corals all contribute a major role for your flow; I have 2 mp40wes in my 90 they are at max flow setting and I still can keep LPS on the bottom wo seeing issue with flow on them as I have rock structures that limit flow in tank, but if I only had thin layer of rocks on bottom of the tank and more of open water then I might have seen too much flow.