What size overflow box?

How do u determine which size overflow box u need and what size return pump for the sump? Im setting up a 55g? Sorry for all the questions lately

 

This is the smallest overflow box that I know about, its rated for 75 gallons but I think that oversizing is always better then undersizing! The max flow is 300 gph so you will need a comparable pump. Hope this helps!

Eshopps PF-300 Overflow Box - Up to 75 gal. | ThatPetPlace.com

 

The CS50 is made for 50 gallon tanks (it's also 300 gph). If you get a CPR overflow box, please remember to also get the AquaLifter pump with it.

CPR CS Overflow Boxes

 

Ya I was looking at the CPR... When it says 300gph is that what size return pump I need in the sump? I assume I have to buy all the plumbing separate?

 

You need to buy a pump rated slightly higher than 300 gph because the pump will be pushing up against gravity, so it loses its strength.

 

Ok thank you! You said to get the aqualifter pump too? Is that what starts the overflow box to start drawing water down into the sump??

 

Yes, and in case of a power outage, it will automatically restart the siphon. I believe that the CPR overflow boxes are the only ones that use that; the other brands start automatically (which is a plus).