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Thread: Pump fills with air when vacuum is connected

  1. Back To Top    #1

    Pump fills with air when vacuum is connected

    i have the same problem today.
    i've had my pool for 10 years and never had this happen.
    today i turned on my filter for the first time this season. all was running well. no air bubbles anywhere and the filter strainer basket was filled to the top with water.
    i connected my vacuum hose to the vacuum head and submerged the length of hose with water eliminating all (99%) of air as usual. I place the skimmer end of the hose, still submerged, through the skimmer opening and stick it with in the hole, same as been doing for 10 years. suddenly the strainer basket fills with air and the pump starts cavitating. this NEVER happened before. i let it run figuring it would eventually even out and fill with water. no such luck. i change vacuum hoses and try again, same thing happens. i gave up on vacuuming for a while, the filter and strainer basket returns to normal. i get a bottle of soapy water and spray every connection, clamp, etc, even spray all hoses and slide my hand up and down each length of hose to ensure everything is soaped up. i see no bubbles, i hear no 'sucking air sound'. i reconnect the vacuum and the basket fills with air and pump cavitates again. now i repeat the soapy water procedure while the vacuum hose it attached, but I still find no soap bubbles and can't find a water leak or air leak. i buy a BRAND NEW vacuum hose. problem not solved. my filter hoses on the suction side are 1 or 2 years old. i've replaced the hose on the return side a few years ago too. any hints on what to do?

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

    Re: Pump fills with air when vacuum is connected

    Welcome to TFP!

    Adding a vacuum hose creates additional suction, which can occasionally turn a trivial air leak into a significant air leak. These can sometimes be very difficult to find.

    Start by checking the gasket on the lid of the pump strainer basket. Make sure it is clean and free of nicks and gouges. Make sure the lid goes back on the pump strainer basket securely. Also take a look at the vacuum plate, if you are using one, and make sure it is intact and free of cracks.
    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

  3. Back To Top    #3

    Re: Pump fills with air when vacuum is connected

    You likely have a very small hose leak. I had this problem for a year not knowing what was causing it until a hose blew. Once the hose was replaced, I no longer had the problem. A year later, the problem returned, so I inspected the hoses. Found a small crack in one, and replaced the flex hose. Problem fixed!
    12' rnd 3500 gal AG Zodiak Waterways Hi-Flo 48 1.5 HP Cartridge Filter

  4. Back To Top    #4

    Join Date
    Mar 2007
    Coastalish 'down easter'

    Re: Pump fills with air when vacuum is connected

    Welcome to TFP, Ted and PK!!

    My usual answer to this is "do you have the 'swivel' end of the hose attached to the vacuum head?"

    With 3 different hoses tried, I'm gonna say that Jason nailed this one

    (BTW Ted, aren't you glad I chose 'waste' and left that username open to you? - I'm also Ted and lived in N.J. for the first 20 years of my life (Tenafly, if you care )
    Luv& Luk

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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