Double pumper? Is that a thing? It is now, maybe.

[G.K.W.H.inthatorder]

Hi all,

Got a question: Bought this pool (5360 gallons) separate from the sand filter&pump (2100gph ). The filter and pump that came with is a cartridge 1500gph...good in the bathtub maybe but not in my pool.
So we have this sand filter pump and no easy place to hook up to because there are only 2 holes and the one is very large and intended for the original skimmer/filter/pump unit (built altogether).
I’m wondering if I can hook the sand filter to the original pump (pressure side) and also, could I run both simultaneously in-line?? Has this been attempted and are there hard lessons to be taught here??
I learned about proper flow rates by volume and the input vs. output of pumps (pool school obviously) and am concerned I might not want to be forcing the flow through my sand filter...sort of like ram-air, but...ram-water??
I’d be grateful for any advice on how to proceed. Thanking you.

(I have pics!?)

 

[kimkats]

Get those pics up so we can really understand what you are dealing with!

 

[G.K.W.H.inthatorder]

Ok, getting the hang of this now...if pics you want, then pics you shall have.

This is pic#1 (original pump, 1500gph) This ugly canister with a cheapo pump inside mounts onto a huge hole in the liner, I have no choice but to leave it there. Ugh.


...and this shall be pic#2
(sand filter pump, 2100gph)

Question is: Can I (should I) run both pumps simultaneously? The main reason I ask is that it seems pump #2 is having to “suck” through pump #1 (at the moment is unplugged and in the way) to do it’s job, with or without a type A cartridge in place inside pump #1. I’m thinking: double the power, double the filtering capabilities, double the fun! Also, pump #2 was expensive for me. Would like to prolong its usefulness if I could by giving some of the workload to pump #1.

 

[kimkats]

I like your thinking! I am going to call in a couple of other people that will KNOW if this is a good idea. I just use my gut but most of the time it is spot on!

Kim

 

[Bama Rambler]

You can try it and it'll probably work as long as the main pump is running on low. If you try to run it on high you're going to overcome the smaller pump and possibly burn it up.

There are also conversion kits that remove the existing pump and then you connect the suction of the external pump to the existing discharge port.

SUMMER WAVES Conversion Skimmer Pumps

 

[G.K.W.H.inthatorder]

Hello Dave,
didnt know they made something for that hole. Also, my main pump(the sand filter pump) is only one speed. AND...if I do burn up that cheapo pump, no big...so long as it doesn’t also burn the liner which it probably would now that I’m thinking about it.
Thank you for the link.

 

[Bama Rambler]

It most likely wouldn't physically burn anything, but it would ruin the little pump.

 

[G.K.W.H.inthatorder]

It most likely wouldn't physically burn anything, but it would ruin the little pump.

You don’t think it could get hot enough to melt a small “you-were-insane-to-even-try-this” hole in the liner??
I think I’m going to go for it. I’ll let you know how it goes. ?

 

[zea3]

I think the smaller pump is going to starve the larger one. Unless you remove the small pump it is going to restrict flow. If you want to run two pumps why not use some pvc and build a suction and return line for the larger pump that hangs over the wall?

 

[Dirk]

Why are you messing with this (is what I would ask)?

I'm with zea. Run the new gear through their own dedicated ports, properly. In the side, or over the side, whatever. Then run the other pump independently, or don't. Remove it and patch the hole. Or don't. Whatever. Why risk burning out pumps, or diminishing their efficiency?

 

[G.K.W.H.inthatorder]

So...works grrrreat! The flow return rate back into the pool is outstanding, like a water park ride! The cartridge in the weak pump catches a lot and the sand filter pump barely sees any action (no bugs, leaves, etc. to clean out of that basket!)

 

[kimkats]

Now run and get 4 floats and all of the kids! Tell them to all get on their floats and ride the water ride!!!

Kim

 

[Costas > DownUnder]

Hello Dave,
didnt know they made something for that hole. Also, my main pump(the sand filter pump) is only one speed. AND...if I do burn up that cheapo pump, no big...so long as it doesn’t also burn the liner which it probably would now that I’m thinking about it.
Thank you for the link.

I think the smaller pump is going to starve the larger one. Unless you remove the small pump it is going to restrict flow. If you want to run two pumps why not use some pvc and build a suction and return line for the larger pump that hangs over the wall?

Adding pumps in series (in-line) does not cause one pump to starve another or restrict flow in any major way. If one pump actually fails/stops there is only a minor restriction present as water will still flow through a stopped pump without too much of an issue.

The overall flow rate through the system is the same through all pumps so it is impossible to 'starve' any of the pumps as such or burn any one of them out.

When you add pumps in series, you normally almost double the overall flow rate (If pumps are identical) for a given RPM. With two different pumps the flow rate will not be double however it will be greater than any one of the single pumps running at a give RPM.

The advantage of running two pumps in series is that you can reduce their RPM way down but still maintain high flow rates.

Just don't run pumps in parallel configurations as that can cause problems.

 

[zea3]

These are not identical pumps. The first pump is 1500 gph and the second pump is 2100 gph. They are both single speed pumps.

 

[Zrock]

You will eventually hurt the new pump as its working 2x as hard trying to pull through the smaller slower pump. Iv seen posts where people just gut the skimmer pump and use it as just a skimmer. Your just increasing your hydro bill for no reason as well.

 

[Dirk]

Your just increasing your hydro bill for no reason as well.

The "debate" about what this is doing, or is going to be doing, to your pumps aside, the redundant pumping, and associated cost in energy use, seems to be a good enough reason to question this setup. But hey, if it works for ya...

 

[Costas > DownUnder]

Not sure why people think that it does not work or that a pump will burn out.....? The science and engineering behind it says otherwise.

It is actually common practice in other industries to run different spec pumps in series to take advantage of increased flow rates.

When combining pumps in parallel then a few precautions must be taken into account but connecting them in series is common and does work.

As the OP has noted, his flow rate has increased considerably due to his overall increase in pressure head.

 

[Zrock]

Big difference between industrial pumps and (no offence I run the same pump..lol) cheap department store pumps. In a industrial setting 1 pump is usually a volume pump and the other is a pressure pump. I would have no issue running a industrial set up in tandem as they are designed for the abuse of a industrial setting

 

[Costas > DownUnder]

Ok, I guess if the OP's smaller pump cannot handle the pressure from the other pump then it may cause it to fail...

Good experiment to see how long it lasts depending on how well the cheaper pump is constructed.

 

[Dirk]

OK, how 'bout this one? (I saw the horse twitch, so I'll have to beat it some more!!)

Run the new pump as it was designed (dedicated pipes and ports). Leave the old pump off. Save the electricity. And save the old pump in case the new one breaks down. Which is more valuable? The benefit of running it in series? Or having a back up pump?