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Thread: Main drain v skimmer and filter pressure differences

  1. Back To Top    #1

    Join Date
    Aug 2011
    Northville, Mi

    Main drain v skimmer and filter pressure differences

    I just noticed that, if I have the diverter completely to the main drain (a dual), the pressure reading on the top of my filter is about 15. As soon as I open it even one tick to allow the skimmer (and all the way until it is just skimmer), the pressure reading is about 20. I also noticed that the pump basket doesn't seem to fill as much when it's completely on the drain.

    Should that be like that? And, if not, what might be making it do that? It almost seems like there's a clog or something in the main drain or line... (but I'm still pretty ignorant about all this stuff...)
    15,400 gal, 16x32 vinyl rectangle (sport dig), Intelliflo VS, 240 sqft cartridge filter, Intellichlor IC40, Mastertemp 250, Dolphin supreme M4 cleaning, Pentair EasyTouch4

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Main drain v skimmer and filter pressure differences

    That isn't an ideal situation, but it isn't surprising either. The main drain plumbing is restricted to some extent. This could be simply because it uses small pipes, or it might indicate a partial blockage of some kind. Either way it is unlikely you will be able to do anything about it.

    Except in special situations you want water to come from both the skimmer and the main drain anyway, so this should be much of an issue.
    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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