I can't run them full blast--tried it and it tore the flesh off of some of my milles.
It's still a work in progress--right now, I have them such that the sand doesn't blow all around, but not sure the placement is ideal. I'll try to get a photo, but just to give you a reference, I have one in the back right corner, one in the front right corner--both of those are close to the surface and directed towards the center of the tank--and then the last one is on the left hand side, almost half way down directed straight across the tank.