Gravity feed gah question

tresguey

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Is there a chart that can tell me max gph on gravity feed pipe ID? Reason why I’m asking is because I have two 3/4” bulkheads and one 1 1/2” bulk head on my overflow. Want plumb my sump for good flow. Not sure if I use the 1 1/2” for the gate valved sump feed and ne of the 3/4 for my return and use the other 3/4 for emergency overflow.
 
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laverda

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3/4” pipe will gravity feed less than 300 GPH. Can you enlarge one 3/4” to 1”? If not I would use the second 3/4” as your main drain. And the 1.5” as a secondary or back up. Depending on the output of your return pump you may or my not have a constant flow of water through the larger drain.
 

ca1ore

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Hard to know for sure. GPH that a siphon will flow depends on more than just pipe diameter … it also depends on the level of head pressure that can be built up over the mouth of the drain as well as the length of drop. For example, I can get 600 GPH out of my 3/4" drain because it drops all the way down to a basement sump. If I had a sump in the stand, I'd be lucky to get half that.
 
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tresguey

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The Tank I picked up has an internal overflow box with 3 existing holes drilled. One in the middle 2 1/2" and on either side I have 1 1/2" holes. Using screw in bulkheads that gives me one 1 1/2" and two 3/4" pipes I can use. I want to use a herbie style plumbing.

I was wondering if I should use the 1 1/2" as the drain because I was concerned I will not get much flow. My return pump is a Various 8.
 
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tresguey

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I plumbed the overflow and return this weekend. Home Depot did not have the 1 1/2" fittings I needed so I decided to try plumbing with 1" pipe instead. I used the 1 1/2" bulkhead as the main drain, but had to restrict it down to 1". Used 3/4" for return and emergency overflow. I set it up Herbie style and the Various 8 on full power was dumping in the emergency overflow too much...by the way, Home Depot did not have any gate valves, so I ran it without. I slowed the pump down 1 speed and the flow was just a bit too slow.

I just ordered all the parts I need from BRS to plumb the drain with all 1 1/2 with a gate valve. Hoping I can run this at full power. I am setting this build up as a Triton style setup and was told I need good turn over through the sump. Currently running a Trigger systems 44 V2 Triton method sump.
 

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