Multiple Return Pumps — Converged or Separated Plumbing?

[nickkohrn]

I am in the process of configuring the plumbing for my upcoming frag system, and I plan to run two return pumps for the sake of redundancy. I have seen plumbing configurations that consist of two pumps being plumbed into the same return line, and I have seen configurations that consist of two pumps being plumbed separately to different bulkheads. I have two return bulkheads, so I could easily have them plumbed separately, but I am not sure which would be best. I am going to be using a Bean Animal drain configuration, which consists of three 1" drains. The bulkheads for the returns will 3/4".

Is one of the options better than the other?

 

[splitting_lanes]

If you run them separately you won’t need check valves to prevent back flow should one pump fail or be turned off

 

[JoshH]

Separately is absolutely the better way to go if you have the option to...

 

[nickkohrn]

If I plumb them separately, will there be a continuous siphon created if I turn one off, resulting in one pump siphoning from the display while the other pumps to the display?

 

[Breadman03]

If I plumb them separately, will there be a continuous siphon created if I turn one off, resulting in one pump siphoning from the display while the other pumps to the display?

I believe so. I'd consider running check valves with the expectation that they function to limit backflow, or make a siphon break. Perhaps running a little RO tube out of a tee and into an overflow would break the siphon.

 

[ca1ore]

I would think if you are going to run dual pumps that you would run them both continuously.

 

[nickkohrn]

I would think if you are going to run dual pumps that you would run them both continuously.

That’s definitely my plan.

The pumps are both COR-15s, connected to my Apex. I just want to ensure that a siphon won’t be an emergency should one fail. I plan to have them configured with matching intensities and schedules, so there shouldn’t be a variance in their duties.

 

[ca1ore]

I would think failure of one would mean a back siphon, though if you are using dual pumps solely as redundancy then a short term siphon wouldn't seem to be that big of a deal - particularly since the siphon would likely lag the remaining return ensuring that some water would continue to go down the overflow. Siphon breaks wouldn't work in this case unless you kept the hole very close to the water surface because the remaining working pump will maintain most of the tank water level. You'd likely have to use check valves, which is Ok in this case because you wouldn't need them to work perfectly, just well enough to slow the back siphon. The checks would restrict flow a bit though.

 

[nickkohrn]

I would think failure of one would mean a back siphon, though if you are using dual pumps solely as redundancy then a short term siphon wouldn't seem to be that big of a deal - particularly since the siphon would likely lag the remaining return ensuring that some water would continue to go down the overflow. Siphon breaks wouldn't work in this case unless you kept the hole very close to the water surface because the remaining working pump will maintain most of the tank water level. You'd likely have to use check valves, which is Ok in this case because you wouldn't need them to work perfectly, just well enough to slow the back siphon. The checks would restrict flow a bit though.

It seems that check valves are the way to go in this scenario. Since I will have two pumps, I could easily clean and inspect the check valves monthly to ensure they are in good condition. Also, the frag system consists of a 40-gallon breeder with a 30g sump, so I don’t need a lot of flow through the returns since I have two MP40s to provide adequate movement where the frags will be housed.

 

[nickkohrn]

Regardless of cost, would you recommend one of these check valves?

 

[DangerDave]

Regardless of cost, would you recommend one of these check valves?

The George Fisher is the quality one. I have used these. They do need to be cleaned every few months to assure they can close. Turning the pumps off to allow them to close momentarily on a daily basis will help keep them clean longer.

 

[lmm1967]

IMO - you're trying to solve a problem that really isn't a problem - and introducing additional potential problems along the way.

1 pump, 1 set of drains (2 or 3 - bean animal, herbie, durso - doesn't matter) - and keep a second pump on hand.
You will not be able to get 2 pumps to remain constant enough to not be constantly fighting it.

If you want redundancy for long term out of town type scenarios....

I set of drains - 2 pumps set up and ready to go, both with flow meters. Apex programming turns on the backup in the event it detects no flow from the primary.

I've yet to see a RELIABLY SAFE setup running dual return pumps out of 1 sump.

I've had multiple tanks utilizing a common sump - even then - I had a single return pump providing flow to both tanks. I tried for about an hour to run 1 pump per tank (using the common sump) - it was pretty much impossible to tune the flow to be stable enough.

Keep in mind - ANYTHING - and I seriously mean ANYTHING - in your drain or return plumbing can and eventually will fail. And I'd be willing to bet that check valves fail much sooner than any other item in your plumbing.

When that check valve fails (it will) - BOOM - you've got a flood to clean up.

Short version of my response = 1 pump running, 1 SET of drain lines, an appropriately sized sump to be able to handle your tank size when return flow is shut off. Venture outside of those guidelines and you will end up with a disaster at some point in time.

 

[nickkohrn]

I’m a bit bummed. I thought that both pumps would fit in my return section, but they don’t. Would it be a bad idea to put one in the empty chamber before my return section? I planned to run my skimmer there, but I can move it to the first chamber instead. Obviously, the ATO sensor will go in the return chamber.

Do you see an issue running one pump in the return section with the other running in the previous section? Or would it be better to get a smaller return pump that will fit in the return section?

The return section is baffled, with the opening at the bottom, which connects the two compartments. That’s because the sun came with a hard filter-floss material to prevent debris and bubbles from getting to the return section, which is in the front of the return area.

Maybe I should take the advice of @lmm1967 and run one pump as the sump was designed for, keeping the second pump free to swap in during maintenance.

 

[jim_fitz]

i have to vectra L1s working on my 500g for redundancy with no problems whatsoever for over 4 years now and they are plumbed separately with 2 x 32mm pipes and 4 x 40mm returns

if one fails yes it will syphon, but if I only had one that would be the case too and then my tank would have no filter

 

[jim_fitz]

and in case everything fails, my sumps base is drilled and i have an overflow pipe which leads to the drain outside

 

[ca1ore]

Regardless of cost, would you recommend one of these check valves?

Although I don’t use check valves anymore, I did prefer swing checks over the wye. Less ‘hammer’ when closing.

 

[Breadman03]

and in case everything fails, my sumps base is drilled and i have an overflow pipe which leads to the drain outside

My tank is two valves from being emptied into a basement drain and takes about 3 minutes for all 150 gallons to be gone.