how many times a hour should the water go through the sump?

[golf nut]

Originally Posted by MikeInToronto

I'd assume you'd cover the intakes with sponges.

Why?

Providing the diameter of the intakes is large enough then the velocity would be very little, what size tank are you wanting to get 10x turnover in? if all you want to keep is Nems then build another box out of egg crate and shove the PH or C/L intake in there.