I run an open sump with 2x-4x flow....I also use a 1000GPH flow pump to avoid detritus settling when it needs to be feeding the million mouths of coral up in the display tanks.
I also run an open sump. I have siporax and chaeto. I run a low power powerhead in order to provide more water contact time for both siporax media and chaeto macro algae.
I run a power head in the first compartment of the sump. It is programmed to come on every hour for 15 minutes. I did this because I noticed detritus settling on the bottom and wanted to "stir it up" to get into the filter socks. Works well.
I run a cheapo powerhead sunsun i belive think its like a 600gph in my return chamber after the refugium. Directly below my doesing lines. To help the does dispurce rather than settle.