I did the fine oolite in my 90 with a 20lb bag.
I also run an mp40.
I used the oolite as a topping above 30lbs of aragonite, and 30 of crushed coral. My CUCs, the first week, turned the sand almost completely upside down.
However, during that time, the mp40 never made it a problem.
Occasionally, my florida fighting conch snail will find something that hasnt been turned and send it back thriugh the turbulence, and it does not seem to become a problem at all.