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Thread: In ground pool leak

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    In ground pool leak

    I have a gunnite inground pool. It's been running fine for 7 years then about 2 weeks ago, I noticed that there was about an unusual water loss overnight.

    I re-filled the pool and tried it with the filtration off and on and the same. About 2 to 2.5 inches gone in a 24 hour period. I tested the evaporation effect by leaving the spa filled and it only looses about 1/2" in the same period.

    There are no leaks in any of the pipes above ground.

    I suspected the underground plumbing so I let the water go down to below the level of all the outlets thinking the water loss would stop. But it keeps dropping.

    So I figure it's the main drain. My first question is - what does the main drain actually do? I don't know that it's actually connected to anything. One explanation I got was that it's just there to equalize pressure. I don't really undersand this.

    Secondly, I'm thinking I'll have to go for a swim and cover the drain with some plastic and see if it stops the leak. Thoughts?
    Concrete (gunite) inground pool and spa (80,000 litres/21,000 gallons)
    Hayward H350 natural gas heater (electronic)
    Goldline Aquarite chlorine generator
    Hayward pumps, Hayward Pro Series sand filter, Goldline valve actuators

  2. Back To Top    #2
    foobert's Avatar
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    Re: In ground pool leak

    How good are you at holding your breath? You could try the dye in a syringe test:

    http://www.youtube.com/watch?v=vlQME1qCWjk

    Of course, completely disable your pumping equipment first -- breaker off.
    ~john
    24.5K G, pebble, SuperFlo VS 1.5, 48sq DE filter, Hayward H250FDN, Autopilot RC-52, Poolvergnuegen & 3 daily swimmers in season.

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    Re: In ground pool leak

    If you find that it is the main drain, it can be plugged and abandoned. There is either a separate suction line from the drain to the pump (with its own valve) or it is plumbed through the skimmer. In the bottom of the skimmer there are two openings, one is the line returning water to the pump, and the other is connected to the main drain. To abandon the main drain that line is plugged at each end.

    Having a main drain improves circulation and provides for draining without the need for a separate submersible pump.
    chiefwej
    Tucson, AZ
    16x36 rectangular (19k) Pebble Tec play pool/spa, Pentair Intelliflo VS 011018, Super II 2hp (spa), Aqua Rite T-15 SWG, Pro Grid 60 DE, Hayward H400 & Heliocol Solar heating, A&A infloor system, fill water w/high CH and TA, 50 ppm borates,TF-100 test kit

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    Re: In ground pool leak

    I went for a rather unpleasant swim (water is green now from lack of circulation) and tried the dye test with some food colouring around the main drain. There doesn't appear to be any water loss around the drain.

    Also, I had no water loss yesterday. This means the only possible culprit is the pool light. Right now, the water level covers about 1/3 of the light so I'm going to refill so the entire light is covered and see if I get the water loss tomorrow.

    I'm really hoping the light is it. If not, it has to be the actual pool vessel itself. What is the likelihood of that in a concrete/gunnite pool?
    Concrete (gunite) inground pool and spa (80,000 litres/21,000 gallons)
    Hayward H350 natural gas heater (electronic)
    Goldline Aquarite chlorine generator
    Hayward pumps, Hayward Pro Series sand filter, Goldline valve actuators

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    Re: In ground pool leak

    What is the likelihood of that in a concrete/gunnite pool?
    Very rare. leaks are almost always found at the penetrations of the shell or the piping.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Guest

    Re: In ground pool leak

    A leak in the main drain is very rare. I do leak detection on about 10-15 pools a week and I hear customers tell me that they suspect leaks in certain places but they hardly ever are where they suspect. First off get your dye syringe out and check your skimmer, and when I say skimmer we are talking about the throat. The flow of water erodes the grout lines and causes many leaks. The 2nd most likely spot is in the light housing. Since 1998 they have been putting plastic light housings in pools and they crack all the time. There is one screw at the top and a hinge in the bottom. Look around the conduit for a crack. A good way to check your plumbing lines fast without pressure testing is close the valve at the pump, cover all but one opening in the pool with duct seal (1.99 at Home Depot), and spray your dye but the one opening that isn't covered. If the dye moves back and forth, that's normal, if it sucks it in you have a leak. If you have any other questions go to my website and look at the info I have on it.

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    foobert's Avatar
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    Re: In ground pool leak

    How strange -- after posting the video link above yesterday, I felt the urge to don the mask and snorkel and go around my pool with dye testing things. Wouldn't you know it, I found a small leak around one of the return outlets. I had a suspicion that the water loss rate had changed recently, and now I know why. I'm losing about 1.5-2" in a week's time -- a bit faster than normal evaporation rate.

    Off to the pool store for some a+b epoxy putty.
    ~john
    24.5K G, pebble, SuperFlo VS 1.5, 48sq DE filter, Hayward H250FDN, Autopilot RC-52, Poolvergnuegen & 3 daily swimmers in season.

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    Re: In ground pool leak

    I filled the pool past the light housing and there's no leak. If there is a leak at the throat of the skimmer, how do you fix it? What sort of grout is used?
    Concrete (gunite) inground pool and spa (80,000 litres/21,000 gallons)
    Hayward H350 natural gas heater (electronic)
    Goldline Aquarite chlorine generator
    Hayward pumps, Hayward Pro Series sand filter, Goldline valve actuators

  9. Back To Top    #9
    Guest

    Re: In ground pool leak

    If the leak is in the skimmer throat and its a grout line we use 2 part pool putty. If its in a plastic skimmer throat we use marine 5200 caulking (available at any hardware store). No matter what the repair or what you are using to repair the leak, the key is prepping the leak. If its a plastic crack use a wire brush first to get the grime off, then hit the plastic with wet/ dry sandpaper. If you are repairing a grout line and using 2 part pool putty, chip out any lose grout, then hit it good with a wire brush. It is very important that the 2 part putty is mixed very good and evenly. Get the putty wet a couple times when you are mixing it to loosen it up a tad and get it mixed well. Do not run the pump for 24 hours after repairs. If your repair is messy when it dries hit it with sand paper or a wire brush to clean it up and make it even.http://www.youtube.com/watch?v=BRsHpaSiKcI This is a good video of where to look in your skimmer.

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    Re: In ground pool leak

    Very informative post, ALD, thank you for sharing.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    foobert's Avatar
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    Re: In ground pool leak

    Patching around the return pipe was remarkably easy to do with the a+b epoxy putty. I scraped the plaster around the pipe and it crumbled into a void hiding behind the skim coat of plaster. Worked the epoxy into the larger void and that sealed it right up.

    Does anyone have any expectation on how long this type of underwater patch job is going to hold up?
    ~john
    24.5K G, pebble, SuperFlo VS 1.5, 48sq DE filter, Hayward H250FDN, Autopilot RC-52, Poolvergnuegen & 3 daily swimmers in season.

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    Re: In ground pool leak

    The time that the patch holds is relevant to how good you prepped the leak and how good the putty was mixed. Let a few days go by and try to dig your fingernail into the putty, if your nail goes in and it crumbles then the putty wasn't mixed properly. In my experience (I do leak detection on around 15 pools a week), patches hold for around 2-5 years. A patch like you are talking about will hold for a long time because it has no direct water flow on it.

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    Re: In ground pool leak

    Update: I was wrong in my previous post. I let the pool sit for a few days and either the leak returned or I didn't measure properly the first time.

    I kept letting the water go down below each shell intrusion and each time, the leak continued.

    1) below the skimmer
    2) below the return lines and vacuum port
    3) below the pool light

    Each time, the leak continued. So it has to be the main drain. I dove down and threaded a teflon coated plug into the pipe that goes from my main drain to the skimmer. It still leaked. Visual inspection of the plug at the bottom of the drain shows no cracking or decay of the expansion plug.

    I now have the pool completely drained. I filled the bowl of the main drain with clean water and I'm watching what happens.

    This thing has me totally stumped.

    On a side note, with the water out of the pool are there any maintenance tasks i should perform? What do I use to clean the gunnite other than water and a scrub brush?
    Concrete (gunite) inground pool and spa (80,000 litres/21,000 gallons)
    Hayward H350 natural gas heater (electronic)
    Goldline Aquarite chlorine generator
    Hayward pumps, Hayward Pro Series sand filter, Goldline valve actuators

  14. Back To Top    #14

    Re: In ground pool leak

    Any comments?
    Concrete (gunite) inground pool and spa (80,000 litres/21,000 gallons)
    Hayward H350 natural gas heater (electronic)
    Goldline Aquarite chlorine generator
    Hayward pumps, Hayward Pro Series sand filter, Goldline valve actuators

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    Re: In ground pool leak

    with the water out of the pool are there any maintenance tasks i should perform? What do I use to clean the gunnite other than water and a scrub brush?
    What does the shell look like? Got any stains that need attention?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Patrick_B's Avatar
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    Re: In ground pool leak

    Quote Originally Posted by duraleigh
    Very informative post, ALD, thank you for sharing.
    A +1 on that.

    It would be nice to see more from an experienced repair person on the forum IMO.

    Nice Post ALD and Welcome to TFP.
    TFP Moderator
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    ABC's Of Pool Chemistry, Test Kits, SLAM Your Pool
    28K Gal IG FreeForm, CLI Quartz, Pentair 36"SF & VS Pump, Dolphin M5, Rheem

  17. Back To Top    #17

    Re: In ground pool leak

    The shell of the pool looks pretty good. There are some calcium deposits around where the spa spills into the pool. And there is a distinct water line but it feels pretty etched in. Probably nothing I can do on that. And it doesn't bother me much.
    Concrete (gunite) inground pool and spa (80,000 litres/21,000 gallons)
    Hayward H350 natural gas heater (electronic)
    Goldline Aquarite chlorine generator
    Hayward pumps, Hayward Pro Series sand filter, Goldline valve actuators

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