Want to build PVC overflow

[Craig Muse]

I know the basic way to build an overflow I just do t know the size pipe to use
im trying to get 500 gph what size pipe should I go with?
thank you

[Andrew_B]

1" pvc is roughly 600gph. If you drop down to even a 3/4", it drops significantly. Online says it drops to about 400gph, but I claim bs on that. It was closer to 200-250gph when I made my pvc overflows a couple weeks back

[mistahoo]

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[Craig Muse]

1" pvc is roughly 600gph. If you drop down to even a 3/4", it drops significantly. Online says it drops to about 400gph, but I claim bs on that. It was closer to 200-250gph when I made my pvc overflows a couple weeks back

Ok so let me ask this, the over flow will only what my return pump will give it right?

[Andrew_B]

Right, you want your overflow to be higher than your return pump. If your drain is 1", you could technically use a 100gph pump and it will drain 100gph (pretending theres no head height). If its a chinese made ebay pump, get a 750ish gph pump for a 1" drain. If its a better, name brand pump, look more towards 600-650gph.

[hungvanvo]

I agree with Andrew, oneinch pvc = 500 to 600GPH . Just add a valve to the return pump oranother end to the sump and it will take care what size pipe you want (1 or 3/4inch )on 500GPH . I just build one overflow 250 Gal and I use 1 and 1/2 inchpipe and have valve control the water flow to my 3 barrel 55Galfilter (outside the house) and return I will use 4000 to 5000 GPH Pump tosupport 4 input to the tank. http://s1315.photobucket.com/user/hu...1a0f1.jpg.html

[TallTexan]

Here's the chart I used, and found to be accurate

http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

Main thing is you return needs to be a minimum 1/2" smaller than your out take.

Discharge is by gravity, so use the first column, return will be pumped, so use second column.

[Craig Muse]

I made 2 overflows (3/4") the same as uarujoey will that be good?

[TallTexan]

I made 2 overflows (3/4") the same as uarujoey will that be good?

I used his design, but single out take.

I used 1" out, and 1/2" in. The 1" barely is barely over what the 1/2" can put in using the 700gph pump.

[Andrew_B]

I initially made my overflow for my 40g with 3/4" pvc. I had zero confidence with it, it just didn't have enough flow (much less than it was suppose to have). Just go with 1x 1" overflow and be done with it. 2 overflows causes issues as 1 is -always- going to be a max capacity while the other will be getting the left over water to drain. It's additional plumbing that isn't required

[troy tucker]

It's additional plumbing that isn't required

I agree no need to have 2 if 1 is done right.

[BiGPiNK]

I agree that two isn't necessary, but if you lack confidence that one will be reliable, wouldn't it be a good idea to have the second day on there to take up the slack should the siphon fail on one of them?

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[Andrew_B]

Sure, maybe 2 of the 1" drains where only 1 is being used and have a second one for backup. But 2 smaller drains when both NEED to be draining so the tank doesn't overflow is a bad thing. Siphons -can't- break unless tampered with and if its a concern, just toss on an aqualifter pump and hook it up to the valve at the top of the pvc and leave it running at all times.