Return Pump Question

[regina13]

I recently bought a 125 gallon aquarium with dual overflows, and was wondering how to decide on a return pump. I do not know what info you need, but just ask if you need to know something. Thanks!

 

[shrimpy brains]

Not sure I'm the best one to answer this, but as I understand it, the inner diameter of the pipes leaving your overflow box will determine gph!
For example: 1" inner diameter pipe would produce 600 gph. If you have 2 this size, I beleive 1200gph coming out of your tanks. Now you have to consider head space (how far up back to tank) so you would want to go with slightly larger pump. Like 1500gph return pump would be good for this example. (I beleive) You can also add ball valve on return to help control return flow, if needed. Hopefully, someone will correct me if I'm wrong. I'm just learning this myself. Hope it helps.