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Thread: Air trapt in Sand filters

  1. Back To Top    #1

    Air trapt in Sand filters

    Fired up for the season- drained, powerwashed, re-filled, opened valves, bled water out of all 4 sand filters. Pump on- good flow. Checked for more air in sand filters and voila- 3 of 4 never seemed to get all the air out, even after letting the air/water mix bleed for an hour. 1 of 4 has never filled with air. Ran pump for week and everyday same 3 of 4 have air trapped. Water levels have never dropped below skimmers and vac lines have been valved off. What's strange to me is when the pump is off, I can bleed all air out, but as soon as pump is on, air comes back. I've backwashed several times and forced air out, but back to filtering and the air returns. Next things I plan to check were leaking/sucking backwash valve and to flush the vacuum lines...what else should I look for? Also, one return/effluent line has been blowing quite a bit of air for the same duration into the pool.

    FYI- 163,000 gal, Im in MD, 7.5 Hp (older then dirt) pump, liquid chlorine, pumps/filters all below waterline.
    The filters are Swimquip High-rate HRP-30's. The sand was replaced 3 seasons ago.

    The head guard doesn't remember the trapped filter air last year (which was her first), but does remember lots of air blowing out one return/effluent line (my predecessor told her not to worry about it...).

    Thanks for any direction!
    163,000 IG 1992 fiberglass overtop 1962 gunnite, 1987 Swimquip Hi-Rate HRP-30 sand filters, 7.5 Hp 3p Marlow Pump; 4,500 IG fiberglass overtop 1962 gunnite, 2008 Hayward sand filter; Liquid Chlorine via Blue-White & Rola-Chem's, High Calcium well water, Located in W. Maryland.

  2. Back To Top    #2

    Join Date
    Mar 2012
    Amarillo, Texas

    Re: Air trapt in Sand filters

    Sounds like you've got a leak somewhere.
    18'x48" AG
    Pentair 1 1/2 HP Dynamo Pump
    Sand Dollar Sand Filter w/ Zeobrite
    Lil Shark Vacuum System
    Hard Plumbed

  3. Back To Top    #3
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: Air trapt in Sand filters

    You have a suction side leak somewhere. Can you post a pic of the equip? We may have some suggestions on where to start looking if you can.
    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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