Sump Return Pump Question

[kentlighting]

Im Putting a CPR 90 on my tank and was wondering what flow rate i should have for my return pump. the CPR 90 claims to have a flow rate of 600 gph. the tank is a standard 55 gallon on a stand. this is the pump im looking at http://www.marinedepot.com/ps_ViewI...twater_Aquarium_Supplies&vendor=&child=RB3115


Thanks in advance guys! (and gals)