Tunze powerhead and controller settings?

[newreefer_59]

I have 4 Tunze 6055 powerheads in my 150 gallon tank (60 X 24 X 24) and the 7095 controller that I would like to optimize with its abilities. But I always seem to have a lot of detritus, etc accumulating on the rocks and bottom of the tank in between my 15% weekly water changes.

Can you forward me advice on where the powerheads should be stratigically positioned within the tank and where the sliding bar should be set on the back. It goes from 12 to 24 volts and I assume the 24 volts puts out a stronger current, but is there a downside to that? LFS said to leave it at 12v?!

Also, I have the controller set on 'sequential' at present. Is there a more optimum setting you would recommend? The tank is a sump set-up with overflow box. Any advise is appreciated.