What size sump pump for my 45g setup?
 

I'm in the process of setting up my 45g cube with a 25g cube for a sump. Probably utilize 18g of the sump.

The head height from sump to the returns is 4'.

What size pump of I need for my sump? Is the Mag 5 @ 310gph at 4' adequate or should I consider the Mag 7 @ 475gph?

Thanks!

Of those two choices I would pick the Mag7.

Also, consider what future item you may like to add.

For example: My return pump also feeds a biopellet reactor and a GFO reactor in addition to tank return... Doing this prevented me from having to have a couple of smaller maxi-jets, etc, in my sump.

Thank you for everyone's advice. I now have a Mag 7 for my 45g cube.