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Thread: Plumbing on Output side of Pump

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    Join Date
    May 2009
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    San Carlos, Sonora, Mexico
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    Plumbing on Output side of Pump

    I vaguely remember seeing a recommendation that on the outlet side of the pool pump (mine is a 1 1/2 HP Pentair Challenger) that at least an 18" straight piece of cast iron pipe be installed before a union before continueing on to other plumbing. I have developed a leak at the outlet of the pump where it connects to the 2" PVC. Should I add this piece of cast iron pipe or simply try to fix the leak using teflon tape or Magic lube? It sounds like Permatex is better but I doubt if I could find it here in Mexico.
    14,000 gallon in ground plaster pool with Hidrazzo goulstrem blue finish with infinity edge and spillover from spa, Pentair challenger 1 1/2 HP filter pump, 2 HP Pentair challenger spa jet pump, Hayward 30" sand filter, Pentair IC40 SWG, Raypack 5100 heat pump, Jandy Aqualink PS8 controls, Kreepy Krauly

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    Re: Plumbing on Output side of Pump

    I can think of no reason to use cast iron. Virtually every pump in the US is installed using only PVC. The 18" of straight pipe is not necessary either, unless you have some equipment it might affect like a flow meter, etc.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Plumbing on Output side of Pump

    I agree with duraleigh that cast iron is definitely NOT a good idea. You want to keep metal out of the water path whenever possible. Most pump mfgrs recommend 4x pipe diameter on inlet side & outlet side of each piece of equipment, but sometimes it's not possible. The straight pipe helps reduce turbulence as the water enters/exits the pump for best hydraulic efficiency. The pump should work well without it, but if you have room, it can help. You'll have to remake the threads going into the pump to fix the leak. Teflon tape or GE silicone will probably work well. Liquid Permatex works well also, if you can find it. Magiclube is not a thread sealant.
    APSP CST Certified
    17k inground concrete; 1.5hp 2 speed Tristar pump, 300sq.ft. Cartridge filter, AquaLogic PS-4 w/ Tcell-15, Navigator suction cleaner.

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    Re: Plumbing on Output side of Pump

    Five times the pipe diameter is a good rule of thumb. 2" pipe = 10" of straight pipe before a turn.

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