size of overflow box ? not sure

[karlyhui]

Hi thanks for reading my post

I have 120 gallon tank with 3 clownfish and a blue tang. They are all very small. I plan to add a Bulb Anemone. No reefs


I brought a used 29 gallon sump and a ehiem 1262 pump I am thinking of either a 600 gph or 1200 gph overflow box.

Which size should I go for? also pvc pipes would I use 1 inch or 3/4 inch.

Thank you

[Avi]

Why don't you get two "600gph" overflows...one on each side of the back of your tank? Use a minimum of one-inch pipe for them.

[fkshiu]

Why would you need anything more than 600 gph with only a 29 gallon sump? You'll have serious micro-bubble issues and your skimmer won't get much chance to pull out much gunk before the water's back up top again.

I've got a 55 gallon sump (~35 gallons actual water volume) with a 135 gallon display and ran a single Lifereef overflow with an Eheim 1260. I had to throttle the 1260 back and even diverted some water back into the sump to get the flow where I wanted.

IMO you should be relying on powerheads/closed-loop for your primary tank flow rather than your return pump.