What size sump pump for my 45g setup?

[WarDog]

Of those two choices I would pick the Mag7.

[ner'T']

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.