DIY overflow box flow rate

chbix

Reefing newb
Are overflow box flow rates pretty standard?

Anyone know the difference between a 3/4 and 1" overflow box rate?

Trying to figure out how big of a return pump I need.
 
FYI this is the design im using,

Overflow

He says between 600-700gph with 1" any idea what would happen if I went down to 3/4"?

I was originally thinking of 1" but all of the return pumps seem to be 3/4", will this cause any problems?

600-700 gph seems high for a 55G tank wtih a 29G sump thats about 7x turnover rate of the whole system per hour.
 
The overflow box should be 9" long and with a 1" pipe you should get around 600 gph. If you are using a 3/4" drain line, the overflow box should be 5" long and you should get around 300 gph.

Drain/Overflow Size
 
I would go with the 1" or possible 1 1/4". Depends on the return pump. What is the GPH of the return pump? Try to match the drain to that number as best you can.

You have to remember that the pumps are forcing water through the pipes where as the drain is just relying on gravity.

If the return pump is 3/4", I am sure that it is putting out quite a bit of flow. I have a mag 7 it has a 1/2" return line and it is a 700 GPH pump.
 
I havent gotten the return pump yet thats why I trying to figure out my drain flow so I can get an appropriate size pump.

Thanks for that link capt thats exactly what I was looking for.
 
Just drill it. The hole saw bits are dirt cheap. There's a hundred videos on youtube for how to drill a glass tank.

Buy your bulk heads first. A 1" bulk head does not fit in a 1" hole. FlexPVC dot com is a great place to purchase bulk heads cheap.

Richon Tools dot com is a great place to purchase hole saws for a couple bucks. They are from hong kong and take a week or 10 days to arrive. They are sent in tiny boxes with chinese stamps. But they are cheapo as hell and they work perfectly. Buy the diamond coated hole saws in the correct size for the bulk heads you select. They come in every size with increments in mm. I always buy 1mm larger than suggested by the bulk head manufacturer.

Bulk head installation 101:
Gasket goes on the INSIDE of the tank.
Hand tighten carefully.
Wrench tighten 1/4 turn
STOP!!
Leak test.

Here is a bulk head flow chart that you can use to size it all.
Bulkhead Flow Rate Art

You indicated a 55g tank and a 29g sump. Typical sump movement is 3x -- 5x the tank volume per hour. So, you want about 90 - 150gph going through your sump.

But you want at least 10x flow/circulation rate in your tank. I've seen and had LPS and softie tanks with 30X turnover. So for a 55g tank you want between 550gph - 1650gph. You'll need some powerheads to make enough water movement in the tank. If I were you, I'd shoot for 1000gph flow and circulation - combined between the sump and the in-tank power heads.

If you just want to move 100-150gph through a sump - all you need is 3/4" drains. Even those would be overkill, but it doesn't hurt to over-design the plumbing for the pump you are going to use.

Assume the pump has a head pressure of 4 feet. That's typical tank height off the floor and your return pump has to fight that vertical rise as well as some elbows and assorted fittings along the way. I've never used a Quiet One pump, but a lot lof people have good things to say about them. A Quiet One 2000 would provide about 200gph at 4 feet head pressure. If it's too much, you can always build a bypass Tee into the return line down in the sump and just divert extra flow back into the skimmer compartment or refugium. That's something a lot of people are doing to gain a flow control advantage instead of just allowing a pump to run wide open.

The outlet on the pump is 1/2 inch. Pipe it all the way back to the tank in 1/2 inch pipe. Don't increase the pipe size on a small pump such as this unless you're going to pipe it like 20 feet or something crazy.

Then you just need enough power heads to get up to 1000gph total system movement.
 
Being my first setup I dont want to commit to drilling the tank.

Thank you for that link!

I found a semi-local shop that has a mag 9.5 pump for $50.

Im also watching/bidding on a few pumps on ebay. Although one is WAY to much flow.

Im curious how the link I posted is claiming 600-700 GPH through the overflow when that data indicates 1" drains average 350 GPH....Seems like the weir Setup with the siphon is basically doubling there results. Melv knows his stuff so im not doubting his claims but curious in the different results
 
Because most overflow boxes state an unrealistic maximum amount of gallons that water can drain.Melev is probably using a more realistic number,if water tries to drain to fast then most overflows will burp and gurgle.

BTW,the return line is never the same size as the drains.Always smaller actually.
 
Being my first setup I dont want to commit to drilling the tank.

Thank you for that link!

I found a semi-local shop that has a mag 9.5 pump for $50.

Im also watching/bidding on a few pumps on ebay. Although one is WAY to much flow.

Im curious how the link I posted is claiming 600-700 GPH through the overflow when that data indicates 1" drains average 350 GPH....Seems like the weir Setup with the siphon is basically doubling there results. Melv knows his stuff so im not doubting his claims but curious in the different results

DRILL IT!!!

It's EASY. $3 hole saw from hong kong - some water - a cordless drill - and about 2 minutes of your life. DONE!! :mrgreen:

Don't be skeered. It's EASY.
 
Back
Top