How much is too much for though sump?

[Ursus]

Im debating whether I should use a return pump thats 900 GPH or 630 GPH in my 20L sump. What do you think?

 

[TKByrnes]

I run a mag 7 at 4 feet of head pumping about 450-500 gph and had a problem with micro bubbles. there was 3 baffles in it and i had to put a filtersock on my skimmer and the drain tubes from overflow. If you use a 20L i recomend more than 3 baffles.

 

[mg426]

3 to 5 times tank volume is all you need through your sump.

 

[Ursus]

Im really just trying to get max flow from my pumps. I suppose I could run the 630 GPH as the return and use a bigger pump for my closed loop than I had planned.

My sump will be setup as follows: Drain/Skimmer section, 3 baffles - U O U, fuge section, 1 baffle - O (possibly a second U baffle behind it, and then the return section.

Now that I think about it, with the fuge in there, even after head loss I think 900 GPH would just be to much for it. Chaeto might get sucked over some baffles or something.

Any thoughts on this setup design?