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Thread: After Vacuuming, lower filter pressure

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    Join Date
    Jun 2012
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    Bolton Ontario Canada
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    After Vacuuming, lower filter pressure

    Hello guys, second post now..just moved into a house woth a pool last August. Opened green this summer, but looking great now. I am a fan of the BBB method, however I am mmissing the test kit part. Being in Canada, my options are limited, although Iam checking to pool store to see if they can order me in a taylor at a reasonable price. Iguess I am utilized what can only be described as a half assed modified BBB, using test strips and liquid Chlorine!

    I do see consisitent tests from my PS, so Ithink I can get buy using that if needed. Last test was 3 days ago:

    FC 5 (only measure to 5, may have been a tad higher)
    CC 0
    PH 7.2
    Alk 110
    CH 200
    CYA 35 - I am using a puck or two a week to subsidize my chlorine and to slowly bring up CYA to 50 or so

    Water chrystal clear.

    Here is my question...my sand filter pump pressure remains fairly steady, even after a backwash at about 15-16 PSI. What I have noticed (last night) is that after I vacuumed the pool, it dropped to 13-14. I did not backwash, only vacuumed. Doens;t seem normal to me.

    Second, I have small bubbles in the returns and at the pump basket. New Hayward pump this year, may be related to that..going to pick up some plumbers grease and try to see if its the lid. No obviouse sign of anything at any connections above ground. How important is it to rectify this? I would describe the amount of bubbles as not a lot, but definately visible at the jets.

    Thanks from Bolton Ontario!
    16x32 vinyl
    80,000L chlorine
    21" Hayward sand filter

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
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    Re: After Vacuuming, lower filter pressure

    The reduction in pressure is likely from the bubbles. It's kinda important to find and fix the leak as you never know when it might get worse and the pump will lose prime.
    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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    Mod Squad zea3's Avatar
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    Re: After Vacuuming, lower filter pressure

    Is the new pump stronger than the old one? If so your water level may not be high enough and you are sucking air into the system. Make sure the water is 1/2 to 3/4 the way up the skimmer. If water level is not your problem then look for a suction side leak. Make sure the drain plug on the pump is snug and the pump strainer lid fits well. You can lube the o-ring on the lid with silicon pool lube to ensure a better fit. Next check the exposed pipes from skimmer to pump and slowly pour water over all the joints with the pump running, looking for spots where water is being sucked in. If you see water being sucked into a joint then that is your leak and the pipe needs to be re-glued or sealed to correct the problem.
    TFP Moderator
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    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
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  4. Back To Top    #4

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    Bolton Ontario Canada
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    Re: After Vacuuming, lower filter pressure

    Thanks for the responses. I have no idea what the old pump was, it is long gone.

    Water level is fine, It's always maintained.

    Just to be clear on the vacumming, PSI before vacuum = 15. PSI immediately after (20 minutes later) = 13.

    Bubble count the same before and after and same as the last few weeks.

    Will try the grease and water. I am thnking it could be a function of the pool guys replacing the pump in some way. I don't think I had any bubbles last year with the old pump.

    Thanks!
    16x32 vinyl
    80,000L chlorine
    21" Hayward sand filter

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    Mod Squad Bama Rambler's Avatar
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    Re: After Vacuuming, lower filter pressure

    You most likely increased the leak a little when vacuuming, but probably not enough to see. The pump will know it because it doesn't take very much air to make a good sized difference to the pumps ability to function.
    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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    Re: After Vacuuming, lower filter pressure

    Ok thanks. If I figure it out I will post it here in a couple days.
    16x32 vinyl
    80,000L chlorine
    21" Hayward sand filter

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    Jun 2012
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    Bolton Ontario Canada
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    Re: After Vacuuming, lower filter pressure

    One other point I just remmebered, maybe will shed some light, maybe not. Last time I backwashed, I noticed after I was done the bubbles were gone. Next time I checked, and hour or two later, they were back. Does that mean anything?
    16x32 vinyl
    80,000L chlorine
    21" Hayward sand filter

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