I have 2 mp10s on my 75 and with the sand I use its plenty of flow. Any more and keeping the sand in the middle of my tank is an issue. But if you had heavier sand or bb than id suggest a third for the back glass. They stay just fine with the thickness of the glass. Mine are higher up on the sides but one is lower than the other. I get good overall flow and the center of the tank is very irratic. Which my sps seem to like.

