How many GPH?

[armyman16]

Okay I bought a sump which came with a couple pumps, one for the sump and one for the return, the one for the return is a CAP 1800 which pumps 628 GPH at 0 feet....what are they talking about with the whole feet thing? Is it the size of the tank or what?
http://www.reefs.org/library/pumps/pumps/cap1800.html
This is the site I am looking at
Thanks in advance!

 

[Mrc8858]

It means the height at which the return is at or "head" the higher it goes the more gravity to fight so lower the gph

 

[armyman16]

Ohh okay! So if the top of my tank, where the power head goes is 4 feet higher than the pump I would need to look at 4 feet?

 

[Mrc8858]

Correct