Return plumbing for dummies

[Whipples]

hi folks, my new tank is coming soon and it's going to be drilled with 2 3/4" returns coming from a single pump. Now I know the 3/4" plumbing itself is somewhat restrictive so I was thinking of running 1" from the return (outlet on return is 1 1/4") to the T and then using the reducers at the T for the two lines going up. Ultimately I'm trying to aim for the 10x turnover for Triton and the headloss calculators have me scared to run 3/4" pipe from the pump up.

New tank estimated total volume will be about 100G, and my return is a 2100gph DC pump. Based on the manufacturers headloss chart I should be in the safe zone with 5' of head or so from the sump to display, but when I put it in a calculator it gives me something like 20+ feet of equivalent head loss! Is that right?

 

[mcarroll]

Two to four times your display's volume gives you a perfect target range for your return GPH.

I'm guessing that your display is 75 gallons or so...

75 x 2 = 150 GPH
75 x 4 = 300 GPH

3/4" plumbing will not be restrictive at all....you can use a reducing Tee to hook the branches up to a 1" main pipe to the pump.

A super-quiet, super-efficient, super-inexpensive Quiet One 2200 (or similar from Sicce, Mag, etc) is all it would take.


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Lifegard Aquatics Quiet One Pro Pumps
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A simple, bullet-proof setup like this with a very simple plumbing layout is almost perfect.

 

[mcarroll]

If you're doing any long plumbing runs or otherwise just want to accurately estimate your final flow rate, try using this calculator: On-Line Friction Piping Loss

Add the head-loss it gives you onto your vertical pumping height before you look up your value on the manufacturer's flow curve. (For 150-300 GPH divided into two 3/4" outlets, the added loss from friction will be near-zero.)

 

[Whipples]

I used that calculator and it calculated head loss at 41'! . Friction was near zero. I pasted it below based on two 90s for the exits (maybe that doesn't matter?) When I take out the 90s it still calculates at 21' of head for a 5 ' piping run. This doesn't make any sense...

Liquid Friction Pressure Loss
Pressure Loss (psi): 17.74 Head Loss (ft): 41
Line Number:
Date: 8/24/2017
Nominal Pipe Size: 0.75
Pipe Schedule: SCH 40
Flow Rate (gpm): 37
Viscosity (cP): 1
Specific Gravity (water=1): 1
Temperature (F): 78
Pipe Roughness (ft): 0.000016
Actual Pipe ID (in.): 0.824
Fluid Velocity (ft/sec): 22.27
Reynolds Number: 142009
Flow Region: Turbulent
Friction Factor: 0.018
Overall K: 5.32
Piping Length (ft): 5
Standard 90 degreeThreaded Elbows: 2
Pipe Entrance: 1
Pipe Exit : 2

 

[mcarroll]

37 galllons per minute!

You need more like 2.5 to 5 gallons per minute. (300 GPH / 60 = 5 GPM)

At 5 GPM, added head loss is less than 1 ft. Perfect. (No coincidence – that's pretty much what the drains and system were designed for.)

Liquid Friction Pressure Loss
Pressure Loss (psi): 0.4 Head Loss (ft): 0.9
Line Number:
Date: 8/24/2017
Nominal Pipe Size: 0.75
Pipe Schedule: SCH 40
Flow Rate (gpm): 5
Viscosity (cP): 1
Specific Gravity (water=1): 1.025
Temperature (F): 79
Pipe Roughness (ft): 0.000016
Actual Pipe ID (in.): 0.824
Fluid Velocity (ft/sec): 3.01
Reynolds Number: 19670
Flow Region: Turbulent
Friction Factor: 0.026
Overall K: 6.43
Piping Length (ft): 5
Short Radius Elbows: 2
Tee Flow Branch : 1
Pipe Exit : 2

 

[mcarroll]

You need more like 2.5 to 5 gallons per minute. (300 GPH / 60 = 5 GPM)

This'll pretty closely track with your skimmer throughput, BTW, if you oversize your skimmer normally. It's nice how these things fit together so well like this.

 

[Whipples]

Oh my gosh I can't believe I did that. I took the raw output of the pump to convert to GPM... Didn't even think to set what the target rate would be. Even with the Triton method 10x turnover I think I would be safe, will likely shoot for somewhere in between your recommendations here and their method and go from there, find some sort of sweet spot! Thank you @mcarroll for ensuring I am not crazy.

 

[mcarroll]

Once you get into flows that high, you end up spending significantly more on the pump and on power.....seemingly for very little additional benefit. Do they say anything about why?

Just some more facts...

If you target >700 GPH, then your friction-loss rises to +3.5'.....for a total head loss of 8.5'.

To get >700 GPH at 8.5 feet you'd need a Quiet One 5000 or equivalent. That's a very efficient pump, but it takes more than 4x the power than the Quiet One 2200 and is roughly double the cost. In most cases, there isn't that much benefit to be had from keeping flows that high.

Even if you bypass the 3/4" altogether and plumb 1.25" PVC all the way from the pump all the way to the tank, getting friction-losses drop back to near-zero, it still takes a QO5000, Mag 12, Syncra 4.0, Syncra MultiQuiet 4000....all seem to be around the same cost as the QO 5000.

So the pump costs and power use are significantly more.

A DC pump can lower power use a bit if you live in a place with really high wattage costs. But I don't trust the durability of non-AC pumps yet and they cost A LOT more....so if you have normal power rates, AC pumps make more sense in this application IMO.

Remember, the QO2200 will do the job at around $60 and has a 5 year warranty....just not at the higher 10x flow rate. A small DC pump is probably at least double that cost....maybe a lot more than double.

 

[Whipples]

I've got a controllable DC pump that I was going to use as I do live in a high-cost area and wanted to give them a shot. They mention it as a way to both get detritus into the refugium/sump to do its job and to maintain more consistency between tank and sump water. It is really just a guideline and is likely going to make my tank a hurricane, just really wanted to make sure I could do it. Pump is a Deepwater Aquatics BLDC8 which based on a head of 9' should be more than capable at ~1500gph should manufacturer numbers be trusted. I will probably aim for the 500gph mark and go from there, tank will be mixed so I might not even be able to pull that off without tearing up my LPS .

 

[mcarroll]

t is really just a guideline and is likely going to make my tank a hurricane

I doubt you'll notice much difference in the tank between 4x and 10x....the majority of flow in the display will be from powerheads. Regardless, if your power costs really are high, then a DC pump could make sense.

However, the BLDC8 is a monster compared to what you need and will still use more power in the process than a smaller, right-sized BLDC. You might consider selling out for a smaller model...but even the BLDC5 is still way, way overkill for 10x....do they make a smaller model than the 5? If not, it looks like Aqua Medic and Current USA do make smaller DC pumps and you might net yourself $100 or so in the switch from the difference in pump costs.....plus the difference in power savings vs the gigantic BLDC8.

2¢

 

[Whipples]

Yeah I went oversized on the pump because I couldn't figure out the calculator ha! At this point I am beyond the return window but am planning to run some sort of manifold off of the return which will put some of that spare power to use. That and I hope I can use it again on an even bigger tank in the future. I really do appreciate the input @mcarroll !

 

[mcarroll]

Good luck!

 

[JLla84]

I'm not here for the plumbing, just to say

Nice avatar!

 

[mcarroll]

I'm not here for the plumbing, just to say

Nice avatar!

That's how it work here.....you come for @Whipples avatar, but you stay for the conversation!