In my opinion, yes, there is such a thing as to much flow. It depends on what you are gonna have in the tank. If you are going for a primarily stoney reef, then you have a little more flexibility. If you are wanting softies, or soft tissued stoneys (frogspawn, bubble coral, etc) then you don't want tons of flow, it can damage them, or prevent them from opening. Plus, those poor fish that have to swim "up current" to get from one side to the other. Just my humble opinion.