Sizing a return pump

ddc0715 · Dec 16, 2020

Thought of the day. I run two 1-1/4 " corner over flow pipes into my sump. what size return pump would it take,to allow me to run those drains wide butt open?an allowing flow control on the return pumpside instead of at each drain. I currently run a little gaint 4 external pump an its to much water for it to handle when pipes are wide open. I have a 150 dt 55g(25TWater) sump an a 10g frag on on the same system

lapin · Dec 16, 2020

Gravity flow on a 1 1/4 pipe is about 1500gph. Your pump I believe is rated 850gph or 1325gph depending on what #4 you have. Then you have head height to factor in for the pump.

DCR · Dec 16, 2020

The capacity of an open gravity drain 1-1/4" line is going to be a much less than 1500 gph, as you have already discovered. Unless you want to make one of these a full siphon, I would be looking for a flow rate after head loss of about 500 gph at most. I would think a Little Giant 2 MDQX-SC, an Iwaki 20 RXT or Pan World 40PX-X might be more appropriate.

theMeat · Dec 16, 2020

1 1/4 gravity fed not full siphon/ meaning with air going down same pipe you’re at around 1000 gph, depending on elbows, horizontal and whatnot

With that said would shoot for 3-5x tank volume regardless.
Also, the less water going down the pipe the quieter it will be.
Will add that you must add in head height to do your figures, and just about all manufacturers way overate their pumps output, except for ehiem

ddc0715 · Dec 16, 2020

My apologies, I do believe I am running 2 fully 1-1/4" siphones drains. An its been a hot minute since I discussed drains, on the left side of my tank is one full siphone and a emergency overflow drain(3/4)an on the right is another fully siphon with the return line 3/4. The 3/4 lines came factory predrilled. Both drains are fully submerged.

Fyi, All is well in the tank, just would like to have flow control on the return line only. At the moment the return line is open wide and I control flow at each drain line.

Is it worth upgrading my pump for this convenience.?

schuby · Dec 16, 2020

So... I'm confused. At first you said you have two, different overflow returns and then later you say you have two submerged, full-siphon drains.

If you have two, full-siphon, submerged drains in your tank and you turn your return pump(s) off, then your tank will drain down to the submerged drains. This would likely overfill your sump and create a flood on your floor. Is that what you have?

theMeat · Dec 16, 2020

Cool
Would still say, no matter your drain capacity, that 3-5x tank volume per hour is the sweet spot.
Personally would get a properly sized pump and leave wide open, or get a dc pump and control it electrically

ddc0715 · Dec 16, 2020

I have two full siphone drains. My floor should not flood unless my tank pops. Flooding was taken into count when the sump design was developed.i used a 55g tank for the sump, which holds only 25 g of water at present. So there is an additional 25g of empty space in the sump to. But this is not the question.

SeaJay · Dec 16, 2020

I run an iwaki 55 in my basement feeding through a 1.25 pipe to dual 3/4 returns. I have two 1” drains and they will outflow the return pump by a looonnnnnnggggg shot. I’m currently getting about 6x total volume turnover per hour. If I supplied enough return to keep up with the drains being wide open, I would guesstimate I’d have about 20x turnover. I don’t see why you would take this approach. Seems a little backward to me. Figure out what turnover you want, then select the pump you need to get there.