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Thread: Main drain vs. skimmer

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    Main drain vs. skimmer

    Hello all. Second thread here. I started one in regards to valve ID: valve-id-identifying-my-valves-t29967.html



    It seems when I turn my main drain/skimmer valve all the way to main drain pressure drops to zero and the basket in front of pump drains. So I haven't kept it there for more than a few seconds. My question is can I turn skimmer completely off and just keep main drain running. If so what other valves need to be on or off.

    Thanks for all the helpful posts.
    *-Arizona-*
    -AO Smith SQ1152 1.5HP
    -15K Gal
    -Jandy JS100-SM Sand Filter
    -Pop Ups
    -In Ground
    -Pebble

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    JasonLion's Avatar
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    Re: Main drain vs. skimmer

    Pressure goes up? Are you sure?

    The main drain/skimmer valve should be the right most valve in the photo, it looks slightly gray and is directly in front of the pump. In the picture it is set to draw from both sides.

    It is not uncommon for a main drain to become clogged, but when that happens and you set it to main drain only the pressure should go way down.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Mod Squad Bama Rambler's Avatar
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    Re: Main drain vs. skimmer

    When you say the pressure skyrockets just how high does it go?
    And what does it normally run?

    You can turn the skimmer off but you most likely don't want to do that. In most applications the skimmer is more important than the main drain.
    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
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    Re: Main drain vs. skimmer

    Yes you guys are right. My bad. It does drop to zero when I turn to MD only. My normal running pressure when set half and half is 14psi.

    Its when I turn my wall return off when pressure jumps up.
    *-Arizona-*
    -AO Smith SQ1152 1.5HP
    -15K Gal
    -Jandy JS100-SM Sand Filter
    -Pop Ups
    -In Ground
    -Pebble

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    JasonLion's Avatar
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    May 2007
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    Re: Main drain vs. skimmer

    That means the main drain is blocked somewhere. The blockage is often right near the main drain, in which case blowing water backwards through the plumbing will sometimes clear it. You could try turning off the pump, set the valve for main drain only, get a garden hose and either something like a Drain King, or a coiled up rag, and seal the garden hose to the inlet pipe inside the pump strainer basket. Then turn on the garden hose and see if it can blow the debris out. When it works it tends to make a mess, but it is a lot simpler than the alternatives.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  6. Back To Top    #6

    Re: Main drain vs. skimmer

    OK. Thanks. I am going to try that now.
    *-Arizona-*
    -AO Smith SQ1152 1.5HP
    -15K Gal
    -Jandy JS100-SM Sand Filter
    -Pop Ups
    -In Ground
    -Pebble

  7. Back To Top    #7

    Re: Main drain vs. skimmer

    OK so I just tried the garden hose method. I saw bubbles come up from the main drain and when I openes the returns the wall inlet by the debris collection system was flowing as well.

    When I put everything back and ran the pump it seemed nothing changed. I can't get any suction from that wall inlet and when turned on only main drain pressure drops and pump strainer basket drains.

    Do I need to take a plunge down to the main drain. Got my scuba gear ready
    *-Arizona-*
    -AO Smith SQ1152 1.5HP
    -15K Gal
    -Jandy JS100-SM Sand Filter
    -Pop Ups
    -In Ground
    -Pebble

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