what size overflow for 90 gallon

[enthb]

Hello, I set up a 125 that had dual corner overflows pre drilled at 1" so I just went from there. I am helping a friend put a 90 gallon reef together. They originally thought they were doing a 75 but got a good deal on a 90. They had already purchased a modular marine overflow with bean animal style drains that is rated for 800 gph and has 1/2 inch drains. The sump has 1 inch drain connections. Should a larger overflow be purchased for this size tank? The other options are 1200gph with 3/4 drains or 1600gph with 1" drains. The 800 overflow box is 8 inches in length, the 1200 is 12 , the 1600 is 16. I had this all planned in my head then the 1/2 inch drain size threw me off. What would be the optimal set up for this? Thanks

 

[lapin]

My ipinion:

Lets say we go with old numbers. 10X turn over for sump. 90g x10 = 900gph. This is a good number. 5 to 7 times would be just fine and works. As long as your friend has power heads in the tank for other circulation and is not planing to have a messy eater like an eel I see no problem with what he has. Be sure to match the return pump to the overflow. Take into account, head pressure ect.......

 

[WVNed]

I would not use 1/2 inch drains on a 90. I have 2 x 1 inch drains on my 75 and it seems about right.
I have a 600gph pump on it. I ran a 900gph and it worked but was really pushing the overflow. There was no adjustment on the gate valve. It had to be fully open.