Dual Return Pumps

[reely989]

I like running two returns. I’ve had pumps act up or whatever and the system keeps chugging. Hell I also keep a third one as a backup in case one fails and I need to swap one out.

 

[xxjt2oxx]

So here is a rough idea of my plumbing. Yellow (3/4") is the front side and pink (3/4") is the back, and they're tied together on the green (1") and down to the pump.

I have an Eshopps Prodigy L on each end of the tank, so the drain pipes from that go straight down and I lose the entire center ~12" of the 24" end. I keep the return lines far enough away from the tank to fit in my Vortechs, which is where space gets tight. The bulkheads for the returns are all 3/4"

That all being said, I never thought about the 1" barb fitting being the current bottleneck. I have the 4 ball valves, and interestingly I have noticed that I don't get much of an increase in flow when I have all 4 wide open vs. 2 open/2 closed, so there may be enough untapped potential in changing that fitting to at least get me to a happy place for now.

 

[UncommonSense]

So here is a rough idea of my plumbing. Yellow (3/4") is the front side and pink (3/4") is the back, and they're tied together on the green (1") and down to the pump.

I see room for even further improvement here, just messing with the three return tees under the tank:

if you can step up to 1.25” Sch.40 PVC (using a 1.25” BSP to 1.25” NPT adapter fitting at the pump, or a 1.25” BSP to 1.5” barbed fitting), that can be reducing tee-d to two 1” sch.40 pipes, which are then themselves reducing teed to your four 3/4” sch.40 pipes…

This would be a perfect-world plumbing scenario which should get you into the realm of realistically moving 10X turnovers that you’re targeting!


However,

have an Eshopps Prodigy L on each end of the tank

These are only rated for 900GPH each!

So, if you use the above plumbing arrangement, reducing 1/4” in pipe size at the outlets of each tee, you will be physically capable of pumping more water into the tank than the drains can handle!

(not with your current pump [<1,800GPH observed after just head loss], but with a bigger pump, this would need to be a consideration!)

 

[xxjt2oxx]

Are the ends of the tank the parts that are "in wall"? No way to go over the overflows?

Eliminating the 3/4" run will help, but 1" is just a lesser problem.

Revising my calculator estimate from earlier to use 1"still gives +5 feet of head pressure.

May not get the target flow with 1", but seems like it should still be enough.

It would also be interesting to me if you were to measure your actual flow rate now before making any changes. Calculations and estimates are nice, but...it's nice to know for sure sometimes. How much flow are you really currently getting?

I see room for even further improvement here, just messing with the three return tees under the tank:

if you can step up to 1.25” Sch.40 PVC (using a 1.25” BSP to 1.25” NPT adapter fitting at the pump, or a 1.25” BSP to 1.5” barbed fitting), that can be reducing tee-d to two 1” sch.40 pipes, which are then themselves reducing teed to your four 3/4” sch.40 pipes…

This would be a perfect-world plumbing scenario which should get you into the realm of realistically moving 10X turnovers that you’re targeting!


However,


These are only rated for 900GPH each!

So, if you use the above plumbing arrangement, reducing 1/4” in pipe size at the outlets of each tee, you will be physically capable of pumping more water into the tank than the drains can handle!

(not with your current pump [<1,800GPH observed after just head loss], but with a bigger pump, this would need to be a consideration!)

2000gph was kind of a rough goal - I feel like the Prodigy would be very difficult to keep silent at full capacity, but that's just my opinion. Realistically I would probably be coming in around 1400gph as my regular use case top end flow.

Long term, I think I'm going to run 2 smaller pumps - one to the front returns and one to the back. I need to look at some of the fittings and really size up the barb section. I like the idea of being able to survive if I'm away or on vacation and not able to get the pump swapped in a timely manner.

 

[UncommonSense]

Long term, I think I'm going to run 2 smaller pumps - one to the front returns and one to the back. I need to look at some of the fittings and really size up the barb section. I like the idea of being able to survive if I'm away or on vacation and not able to get the pump swapped in a timely manner.

In this case, I’d say stick to two 1” pipes, one for each pump… this way, you can omit the check valves completely by having each return pump on fully independent plumbing!

If vibration mitigation is required, you would 1.25” tubing/barbed fittings for each pump to maintain the usefulness of 1” pipe; moving 700GPH+ with minimal frictional flow losses! (Basically, maximum observed GPH per-watt of power consumed)