I got them from Drs F&S. I am still new at this, but I think there is a lot of flow. I have them angled up a bit, also. Pointing them straight at each other (or even downward) would increase the turbulence. I was tempted to get the 4s, but seeing what the 3s do, I think that may have been too much. I have a sandy bottom, and have not started any of the more demanding sps corals, but for me these seem great.