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Thread: Help diagnosing low suction at skimmer

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    Help diagnosing low suction at skimmer

    20k gallon in-ground
    1-1/2" piping
    1 skimmer
    2 ports below skimmer basket. 1 to the pump and 1 to the main drain.
    No valve to distribute suction between skimmer and main drain
    1 valve to distribute return between 1 return port and all the other ports (not sure of the reason for this or the function it serves)
    Hayward Super 2 Pump (1hp) w/ a new AO Smith B128 motor (old motor had worn bearings)
    Auxiliary pump for cleaner
    DE filter recently inspected, cleaned, and recharged


    My wife and I recently bought an older house with an older pool. It seems to have been maintained well enough, but I don't believe I'm getting a sufficient amount of suction at the skimmer. Leaves and bugs will float right by the skimmer entry, but not get sucked in. It seemed to have a much stronger flow when we initially moved in to the house, but I admit I didn't do much with the pool other than empty the basket, skim the surface, and run the vacuum during the winter.

    The pump is definitely moving water. There are no air bubbles to be seen under the pump lid or out the return lines. When the cleaner pump kicks on, the Polaris moves around properly and picks up debris.

    I tried a drain king inserted in to the pump inlet. Nothing came back up the skimmer line and I could definitely feel the cold water from the hose coming up through the port. The impeller is free of debris as I checked it when I swapped the motor (same symptoms before and after motor swap).

    Any thoughts?

    Thanks,
    Matt
    20k gal, IG fiberglass, 1 HP Hayward Pump, 36 ft Leslie's DE Filter, Polaris Cleaner

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    Re: Help diagnosing low suction at skimmer

    Are the weir doors installed? Do you have the water up about 1/3 of the way on the skimmer opening?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Help diagnosing low suction at skimmer

    The water is about half way up the skimmer opening.

    There isn't a weir door. The pool doesn't even have a way to mount one that I can tell, but I assume there is a generic spring mount option or something. Isn't that just to keep debris from floating back out in to the pool when the pump is turned off?

    Thanks,
    Matt
    20k gal, IG fiberglass, 1 HP Hayward Pump, 36 ft Leslie's DE Filter, Polaris Cleaner

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    Mod Squad Bama Rambler's Avatar
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    Re: Help diagnosing low suction at skimmer

    The weir is for more than just keeping stuff from returning to the pool. It also drastically improves the surface skimming action.

    You say that the main drain is connected to the bottom of the skimmer? Is there a diverter in the bottom of the skimmer?
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Help diagnosing low suction at skimmer

    Interesting. I'll see if I can add a generic weir.

    Yes, the diverter valve is present. Sorry, I forgot to mention that in my original post.
    20k gal, IG fiberglass, 1 HP Hayward Pump, 36 ft Leslie's DE Filter, Polaris Cleaner

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    Re: Help diagnosing low suction at skimmer

    I mentioned in my original post that it seemed like there was more suction originally and, the more I think about it, I'm certain that was the case. When we first bought the house, the skimmer basket was completely stuffed with leaves as was the basket in the pump. When I cleared those out, I remember turning the pump on and seeing things on the water surface heading towards the skimmer.
    20k gal, IG fiberglass, 1 HP Hayward Pump, 36 ft Leslie's DE Filter, Polaris Cleaner

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    Mod Squad Bama Rambler's Avatar
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    Re: Help diagnosing low suction at skimmer

    What is the filter pressure?
    When was the last time you disassembled and cleaned the filter?
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Help diagnosing low suction at skimmer

    I disassembled and cleaned the filter a few weeks ago. I didn't find any tears or damaged areas. I did wash a lot of debris out of the filter. I'm in Austin, TX and we have trees near the pool that drop a brown fuzzy material. I'm not even sure what it is, but during the fall and winter, a lot of it ends up in the pool.

    The pressure sits at about 12psi after I backwash and add DE. It's currently slightly above that.
    20k gal, IG fiberglass, 1 HP Hayward Pump, 36 ft Leslie's DE Filter, Polaris Cleaner

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    Mod Squad Bama Rambler's Avatar
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    Re: Help diagnosing low suction at skimmer

    Is the pressure reading about the same as it always has?

    Have you checked the pump impeller to see if there's a partial clog?
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  10. Back To Top    #10

    Re: Help diagnosing low suction at skimmer

    I've checked the impeller and it's not clogged and doesn't appear to be damaged in any way.

    I believe the pressure readings are consistent.

    I should also note that the flow doesn't appear to improve when I move the valve to recirculate. If I understand it correctly, that should take the filter out of the equation.
    20k gal, IG fiberglass, 1 HP Hayward Pump, 36 ft Leslie's DE Filter, Polaris Cleaner

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    Mod Squad Bama Rambler's Avatar
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    Re: Help diagnosing low suction at skimmer

    It does take the filter out of the loop, but on my filter, the head difference between filter and recirc is minimal.

    The flapper on the diverter in the skimmer hasn't gotten moved has it? Drawing more from the MD.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  12. Back To Top    #12

    Re: Help diagnosing low suction at skimmer

    The flapper is open fully.
    20k gal, IG fiberglass, 1 HP Hayward Pump, 36 ft Leslie's DE Filter, Polaris Cleaner

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    Mod Squad Bama Rambler's Avatar
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    Re: Help diagnosing low suction at skimmer

    Everything seems the same as always so I'm at a loss.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  14. Back To Top    #14

    Re: Help diagnosing low suction at skimmer

    I'll try to install a universal weir. I'll report back my findings. Thanks for the effort.
    20k gal, IG fiberglass, 1 HP Hayward Pump, 36 ft Leslie's DE Filter, Polaris Cleaner

  15. Back To Top    #15

    Re: Help diagnosing low suction at skimmer

    I have had similar problems. Get a properly functioning weir door and keep your water level up. That could be all you need to do.
    Walnut Creek, CA. 18k gallon Pebble Sheen + 1.5k gallon IG spa, 1.5hp whisperflo main pump, Pentair clean and clear 420, Intellichlor IC20, Polaris 360 w/booster,Jandy lite 2 natural gas, plus solar with Heliomatic 5000 controller and 3/4 hp booster

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