What size return pump?

[christensonjes]

I am in the process of getting a 75 gallon tank with a 30 to 40 gallon sump. Is a mag 7 good enough or should I go bigger? What is the advantage or disadvantage to going with a bigger pump? Thanks

[mtfatwork]

depends on the flow rate of the overflow. Mag 7 is 700 gph give or take. Are you using hang on style overflow box, or are we talking drilled and built in overflow?

[christensonjes]

Drilled. 2 mounted overflow boxes. 1'' Holes

[rihanssu]

I use a mag 5, even though people told me to move to a bigger pump here is my reasoning for staying with the mag 5;
i wanted the water to be in the sump a little longer so the skimmer (and in sump model) could get to more of it. ALSO wondering whats the reason for a sump if you don't want water in there? its nothing more then a fancy closed loop otherwise.

[redwinger]

Depends on your tastes really and your system. Lots prefer a slower turnover rate. I prefer to max the overflow GPH so I can get all the crap out as fast as possible. Your skimmer throughput needs to be the same or relatively close to the overflow GPH in order to make a difference. Ex. overflow 600gph, skimmer should be at 600gph give or take 100gph IMO.