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Thread: pump "pulling vs pushing"

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    pump "pulling vs pushing"

    OK here goes. My pool originally had a small, fiberglass type water fall 5' wide by 3' long by 3' tall. 1 1/2" plumbing was installed tied to a separate pump. Behind my pool is a 7' retaining wall. I recently removed the prefab waterfall and built a rock waterfall from the retaining wall to the pool. It is probably 10' wide and 7' tall, cascading down three tiers into the pool. My pump is at ground level, with the output side originally running about 30' in length, then up the 7' into the holding area for the beginning of the waterfall. I am not getting enough water to fill the holding pool and create enough of a waterfall, so this is my question. I am thinking of trying one of three things.
    1. Keeping the original pump (1 1/2 hp) in place and installing another in line at the top of the retaining wall. Will it be plausible to plumb from one pump into another?? Would this take care of friction loss, the overall long length of the run and the rise in elevation and hopefully increase the water at the holding pond??
    2. From where the 1 1/2" plumbing comes out of the ground, what if I "t" off and plumb the two pumps separate, giving me two separate outputs. My question is can the one 1 1/2" line from the pool supply two separate pumps, or would they try to "suck" from each other??
    3. Would simply moving the location of the pump from the current position to the top of the retaining wall help. This would make the pump "suck" the water the entire length and rise of the plumbing and "push" it out just a few feet from the holding pool instead of "sucking" at ground level and then "pushing" it the entire length and rise. Which would be better.

  2. Back To Top    #2

    Join Date
    Feb 2008
    Denton, TX

    Re: pump "pulling vs pushing"

    Welcome to TFP!

    It does sound like you are going to need to add a booster pump into the mix there.

  3. Back To Top    #3

    Re: pump "pulling vs pushing"

    Such as a booster pump that is used with a "Polaris"? Should it go in front of the pump, or on the output side?

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: pump "pulling vs pushing"

    The largest improvement you could make would be to switch to 2" pipe or better yet 2 1/2". After that the next step would be to use a larger pump in the same location as your current one. Putting two pumps on your current pipe would help only a little, and would have some minor complications, for example multi-pump systems are much more difficult to prime correctly.

    A typical in-ground pool pump is designed to be able to raise water several feet from below the pump, and push much further above the pump, ie 30 or 40 feet. So putting a pump up on top of the waterfall isn't such a great idea. It would kind of work, but there are much better approaches.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: pump "pulling vs pushing"

    Pool pumps love to push but they hate to pull.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  6. Back To Top    #6
    mas985's Avatar
    Join Date
    May 2007
    Pleasanton, CA

    Re: pump "pulling vs pushing"

    Have you ever tried to pull water?

    Water is actually "pushed" on both sides of a pump. On the suction side of the pump, the pump creates low pressure and it is the atmosphere that pushes the water to the pump. Same principle as a straw.

    Anyway, to get a high volume of water, you need large pipes and a large volume pump (i.e. waterfall pump). What type of pump are you trying to use (i.e. what is the make/model)?
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
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  7. Back To Top    #7

    Re: pump "pulling vs pushing"

    I cannot change pipe size, it's and inground pool. All pipe is 1 1/2". I have a Hayward 2 hp. Original plumbing had a horizontal run of around 25 or 30', then up 7', the another 5' horizontal. Broken pipe caused replumbing, now 3' horizontal, 7' up, then 25' or 30' horizontal. Now it doesn't flow near as much water as before. If pumps like to "push" more than "pull", it evidently won't do any good to T of and install a second pump on the output side. I am now thinking that I might take the booster pump for the Polaris and plumb the output side into the holding pool.

  8. Back To Top    #8

    Join Date
    Apr 2013
    Central Florida

    Re: pump "pulling vs pushing"

    Typically you don't lose a lot in the horizontal runs. Some, but not much. The real place you lose flow rate is the head pressure and that is the same amount (7') as it was originally.

    There must be something else going on here.

    Can you disconnect the pipe at the pump and just measure the pumps output? Like plumb it straight into a 33 gallon trash can and time how many seconds to fill it?

    If it worked before then maybe something is clogged or restricting the flow in the "new" piping arrangment. Or maybe something got into the impeller.

    If it worked before it should still work.

    My Pool: 17K gal IG Diamond Brite/gunite with Hayward 100 sq. ft. cartridge Filter, Hayward 1 HP pump, and a TF-100 Test Kit

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