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Thread: Air in return line

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    Join Date
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    Air in return line

    I have bursts of tiny air bubbles coming out of one of my 2 return lines. Everything i have read indicates that this is a sign of a suction side leak. I notice that there are a fair amount of bubbles in my pump. When i close the valve to the return line that is pushing air into the pool the bubbles in the pump disappear and the pump is crystal clear. when i open the valve the pump immediately fills with bubbles and air starts to enter the pool again. I am thinking that this would indicate a supply side leak? I appreciate any suggestions.

    I have a 30,000 gal inground liner pool with a brand new Hayward pump and 2 year old filter.

    Thanks,
    Mike

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    Casey's Avatar
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    Re: Air in return line

    Welcome to TFP Mike!

    Someone will be around shortly to help you with your leak.
    I'd bet you my bikini you'll never get TFP water from a pool store!

    24' Sharkline Venture De Filter

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    Richard320's Avatar
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    Re: Air in return line

    Welcome! :wave.

    I'm guessing that when you shut off that one return and the bubbles stop, the filter pressure rises one or two psi. Without trying to explain it all, it does sound like a suction side leak. The most common ones are low water level in the pool so you have a vortex in the skimmer, a sticking weir (flapper) in the skimmer causing the same thing, loose drain plugs on the pump, or a bad seal on the pump lid. Even a blade of grass stuck to the O-ring under the lid can do it. a hairline crack in the rubber. Even an old stiff O-ring that has hardened with age can do it. Then you get to pretty rare things like leaking fittings or valves or cracked pipes.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Air in return line

    Thanks Richard. All great suggestions.
    The pressure does go up about 4 psi. (is it safe to run it on one return?).
    The low water level has happened before and now I keep the water level very high. A fraction of an inch below the top of the skimmer.
    Plugs and o-rings are all perfect. The equipment is in a pool house and perfectly dry cement around that side. However, sometimes (today) the concrete is slightly wet around the return side.
    I suspected I had a leak last year and had them pressure test this spring and they said it was fine. However, I can't get my head around the fact that opening that one valve on the return side throws air into the system. In my mind it can only be a leak in that line.

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    gtemkin's Avatar
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    Air in return line

    When I have a small suction side air leak the bubbles always come out of only one of the returns because bubbles rise in water and will exit the return whose plumbing is slightly higher than the others. You have a classic small suction side air leak. If the air leak was massive, then you would see air coming out other returns. The fact that you don't see water leaks in the suction side plumbing doesn't mean anything because you have a small air leak where air to be sucked in, not water pushed out, especially because the water isn't under any pressure because the leak is on the suction side of the plumbing.
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: Air in return line

    Makes sense to me now. Now, if the leak is not visible on the equipment i must assume it is underground. Would a small leak show up when they pressure tested? Is there another way to try to locate it?

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    gtemkin's Avatar
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    Re: Air in return line

    Quote Originally Posted by mlaforge View Post
    Makes sense to me now. Now, if the leak is not visible on the equipment i must assume it is underground. Would a small leak show up when they pressure tested? Is there another way to try to locate it?

    Unfortunately the leak will not be "visible". Suggest you read the article in Pool School>Solving Problems>Suction Side Leaks. It has good suggestions on detecting those type of leaks. Also suggest you assume the leak is above ground and double, triple and quadruple check the above ground situation before going after underground leaks. It's most likely above ground.
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: Air in return line

    Will do. Thanks for the help. I have isolated it to on skimmer but not able to determine where yet. I will check out the suggested thread.

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