[patsfan1130]

I am unsure of the make of my overflow but I can tell you that the outlet is 1''. I believe this is pretty standard. My box has a plastic butterfly screw so I can adjust the height on the inside of the tank. My first question is...Do I want the slots on the box JUST below the water line? halfway? Is there a standard here?

Also...I have 2 pumps to choose from for my return. A RIO 2100 & a 2500. which would be best? I know I know, ROI pumps are NOT the pumps of choice & I will replace it soon enough. But for now...I own these pumps & would like to set this up.

I'm setting this up on a 75g and using a 20L as a sump.

Thank you

Mark

[Poseidon]

I don't know of any rule of thumb, as far as the overflow box goes. Just set it so that MORE water can go down the overflow, then can come back from the pump. That way it will be easy to establish a balance, as only the volume of water coming back from the pump will be able to go into the sump. It is hard to type out, but just tinker with it a while, and you will get it figured out..