Return size for new build

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Redtail Catfish
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Putting a new build together roughly 400 gallons. Just ordered two jebao dcp-10000 pumps rated at max 2650 gph. I plan to run them 1200-1500 gph each in a dual sump setup, each pump routing to its respective return.

The back panel came off another one of my tanks and ive set it up with three 1.5" drains and two 3/4" returns.

20200323_140950.jpg

Are these 3/4" returns too small for my new pumps? If so what size would be ideal?

Thanks MFKers
 

Siddons11

Piranha
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Sep 19, 2012
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3/4 will work but won't be as efficient as 1" or even 1.5" plumbing. What you could do is use 1" or 1.5" then reduce down to 3/4 at the bulkhead if you're worried about drilling new holes. This will decrease head loss significantly.

If you are fine with drilling new holes then 1.5" will be the most efficient for sure.
 

Backfromthedead

Redtail Catfish
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3/4 will work but won't be as efficient as 1" or even 1.5" plumbing. What you could do is use 1" or 1.5" then reduce down to 3/4 at the bulkhead if you're worried about drilling new holes. This will decrease head loss significantly.

If you are fine with drilling new holes then 1.5" will be the most efficient for sure.
Really? 1.5"? I just don't understand how making the returns bigger is easier on the pump. Must be true though because people keep telling me that.

I always figured smaller return lines were better because its less water to push through the hose.

I shall mull it over. Maybe one pump can go to both bulkheads and another one over the back.
 

Oughtsix

Dovii
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Apr 9, 2011
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Really? 1.5"? I just don't understand how making the returns bigger is easier on the pump. Must be true though because people keep telling me that.

I always figured smaller return lines were better because its less water to push through the hose.

I shall mull it over. Maybe one pump can go to both bulkheads and another one over the back.
You are correct. The smaller the return line -> the less water will flow through the return -> the less work will be done by the pump -> the pump is working less so it will be drawing less power.

The Jebao DCP 10000 is a big pump. By using such small (3/4") returns you are seriously restricting the max flow you will be able to push through the pump. Why buy such a big pump if you are going to restrict the possible flow through it so much? There is a good chance you won't even reach 1200 gph with 3/4" returns... (I didn't actually look up the flow rate for 3/4" pvc but from experience that sounds very small).

-- I would use the low pressure column in this table: https://flexpvc.com/Reference/WaterFlowBasedOnPipeSize.shtml

I plan on running a DCP-12000 or DCP-15000 on my 180g tank. I am plumbing for 5 x 1" returns for the single pump with 1.5" PVC feeding the manifold for the manifold reducing it to the 1" returns.

It is very easy to back down the flow on the Jebao DC pumps if you are getting too much flow through 1" returns but that is a big pain in the rear if you find 3/4" returns are too small to give you the flow you want and you have to tear out and re-pipe your returns.
 
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Backfromthedead

Redtail Catfish
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You are correct. The smaller the return line -> the less water will flow through the return -> the less work will be done by the pump -> the pump is working less so it will be drawing less power.

The Jebao DCP 10000 is a big pump. By using such small (3/4") returns you are seriously restricting the max flow you will be able to push through the pump. Why buy such a big pump if you are going to restrict the possible flow through it so much? There is a good chance you won't even reach 1200 gph with 3/4" returns... (I didn't actually look up the flow rate for 3/4" pvc but from experience that sounds very small).

-- I would use the low pressure column in this table: https://flexpvc.com/Reference/WaterFlowBasedOnPipeSize.shtml

I plan on running a DCP-12000 or DCP-15000 on my 180g tank. I am plumbing for 5 x 1" returns for the single pump with 1.5" PVC feeding the manifold for the manifold reducing it to the 1" returns.

It is very easy to back down the flow on the Jebao DC pumps if you are getting too much flow through 1" returns but that is a big pain in the rear if you find 3/4" returns are too small to give you the flow you want and you have to tear out and re-pipe your returns.
Very good explanation. Makes more sense to me now. Thank you.

So would you say 1" return lines and bulkheads would be ideal in my case? or should i go 1.5" or even 1.25"? I suppose redrilling the returns wont be too much work.
 

DN328

Aimara
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Aug 14, 2014
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I've used DC pumps as return pumps and closed loop circulation pumps. In all my cases I've used PVC plumbing and what I typically do is stay with the same diameter of the pump outlet. I then "T" off to two 3/4" bulkheads where I typically will use loc-lines. I've noticed many DC pumps (not all) these days have a 1.25" outlet. So you could run that size out then split/T into two 3/4 returns, etc. I realize the benefits of a DC pump is being able to control flow. I just try my best to not restrict output.

edited for clarity.
 
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Backfromthedead

Redtail Catfish
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I've used DC pumps as return pumps and closed loop circulation pumps. In all my cases I've used PVC plumbing and what I typically do is stay with the same diameter of the pump outlet. I then "T" off to two 3/4" bulkheads where I typically will use loc-lines. I've noticed many DC pumps (not all) these days have a 1.25" outlet. So you could run that size out then split/T into two 3/4 returns, etc. I realize the benefits of a DC pump is being able to control flow. I just try my best to not restrict output.

edited for clarity.
Thank you. The old tank was plumbed like youre saying, 1" from the pump, with a Y splitter to the two 3/4" returns. I think I'll run one sump/pump just like that again, and the other over the back of the tank.
 

Backfromthedead

Redtail Catfish
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I’m running two dcp-15000s and use 1-1/2” for the return plumbing. I’m running them about 4000 gph at 50%
Yeah ive kept up with your build and have noted your support for large return plumbing. Ive just never been able to wrap my head around it but i guess the 15000s are substantially larger pumps than im used to working with.
 

TheWolfman

Giant Snakehead
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Yeah ive kept up with your build and have noted your support for large return plumbing. Ive just never been able to wrap my head around it but i guess the 15000s are substantially larger pumps than im used to working with.
Some great points were made above. I don’t agree with the smaller diameter plumbing causing the return to draw less power though. If anything smaller plumbing will put more strain on the return pump and shorten it’s life span. One thing to consider is your target turnover and pump size. If your return pump puts out a max 2650 at zero head height. Factor in head height and 90s and your going to be at about half that. You will also be running them at 100% duty (another thing that will shorten pump life) I would consider a larger return and throttle it back to insure you have the turnover your shooting for.
 
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