Pump size

[hanmisi]

How do you know what size pump you need on your tank? I have a rio 17 HF on my tank right now but I am going to buy a new pump this one is going out, I was thinking about getting smaller pump, but how do I know how what size to get, I have a 40 gal breeder with a 30 gal sump with two output and two returns.​

 

[florida reef]

Why don't you stick with the same size and just install a valve on the return line so you can adjust the flow rate at any time? That's what I have and It helps a lot sometimes. As far as the pump size, it would depend on your overflow size and how much water is entering the sump.