Time to buy a pump but I need some help

[Johnny Reefer]

I use a Hagen Aquaclear 901/110 powerhead on my present 180g with 33g sump system. They push 900 gph at 0' head. My head is at 4' approx. (makes me sound short) so that calculates to about 750gph, if I remember correctly. But I have two 6" corner overflows, not just one, for a total of 24" linear overflow. You should determine how much gph your overflow can handle (there is a calculator on Reef Central), factor in the head, and then size your pump accordingly so it doesn't exceed the linear overflow capacity.

HTH,