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Thread: Slow Leak - Just Ignore?

  1. #1
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    Slow Leak - Just Ignore?

    Last fall before closing I thought I might have a leak, since I seemed to have to top off the pool water more frequently than in past years. Yet that need seemed erratic. Did the bucket test several times, and did not get consistent results. Before closing, I squirted dye around the most likely areas and did not notice anything. I suspected the leak might be in my skimmer return line, and figured that would be easy to tell once I lowered the water level.

    Over the winter, it has become clear that I have a leak - and that the problem is not (or at least not only) the skimmer return line. But the leak is slow - about 1/16" per day, and thus very hard to detect in an overnight bucket test. but clear over the course of weeks. In my pool, that's about 25 gallons per day.

    My guess now is that the problem is in the bottom drain return line. I say this in part because I can't think of other options. But also it seemed to me last summer that I didn't notice a drop in water level for a while after heavy rains; the rise in the water table might have kept that pvc return from leaking.

    The deep end of my pool is about 8 1/2'. I can't imagine digging to try to gain access to that return. But I don't think my pool water will circulate very well If I just cover the bottom drain and close the return to the bottom drain at the pump.

    So what to do? Should I just live with the leak, monitoring water loss to be sure it doesn't increase? Or do I really need to cover my bottom drain? Is there another alternative?
    22,000 gal, IG vinyl, 3/4 hp pump, 300lb sand filter (switched from DE), converted from baquacil (thanks to Ben), BBB since 2004

  2. #2
    Senior Member polyvue's Avatar
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    Re: Slow Leak - Just Ignore?

    Quote Originally Posted by tcpiii
    ... I suspected the leak might be in my skimmer return line, and figured that would be easy to tell once I lowered the water level.

    Over the winter, it has become clear that I have a leak - and that the problem is not (or at least not only) the skimmer return line. But the leak is slow - about 1/16" per day, and thus very hard to detect in an overnight bucket test. but clear over the course of weeks. In my pool, that's about 25 gallons per day.

    My guess now is that the problem is in the bottom drain return line. I say this in part because I can't think of other options.

    The deep end of my pool is about 8 1/2'. I can't imagine digging to try to gain access to that return. But I don't think my pool water will circulate very well If I just cover the bottom drain and close the return to the bottom drain at the pump.

    So what to do? Should I just live with the leak, monitoring water loss to be sure it doesn't increase? Or do I really need to cover my bottom drain? Is there another alternative?
    Don't rule out other possible locations. Did the water level drop below your light niche, for example? Are there other pool suction/return lines that are below the skimmer?

    If you determine that it is the deep end drain, there are other ways to circulate the pool water (my auto pool sweep does a fine job of this.)
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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    View of spiral galaxy in Ursa Major NGC6217 - Hubble Telescope 2009

  3. #3
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    Re: Slow Leak - Just Ignore?

    Quote Originally Posted by polyvue
    Don't rule out other possible locations. Did the water level drop below your light niche, for example? Are there other pool suction/return lines that are below the skimmer?

    If you determine that it is the deep end drain, there are other ways to circulate the pool water (my auto pool sweep does a fine job of this.)
    Thanks for the thoughts. My winter water level is not below the light niche. I have done the dye test around the light, however, and don't notice any movement of the dye. The returns are all above the winter water level.

    I do have one spot in the vinyl which is scratched - perhaps from when the brush broke off the pole while one of my sons was sweeping. That's about 6' deep, and I haven't figured out how to do a dye test there. If anyone can point me to a thread that discusses how to test deep leaks like that, I'd be appreciative.

    If I rule that out, I think it has to be the bottom drain.
    22,000 gal, IG vinyl, 3/4 hp pump, 300lb sand filter (switched from DE), converted from baquacil (thanks to Ben), BBB since 2004

  4. #4
    Senior Member polyvue's Avatar
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    Re: Slow Leak - Just Ignore?

    Quote Originally Posted by tcpiii
    Thanks for the thoughts. My winter water level is not below the light niche. I have done the dye test around the light, however, and don't notice any movement of the dye. The returns are all above the winter water level.

    I do have one spot in the vinyl which is scratched - perhaps from when the brush broke off the pole while one of my sons was sweeping. That's about 6' deep, and I haven't figured out how to do a dye test there. If anyone can point me to a thread that discusses how to test deep leaks like that, I'd be appreciative.
    A dye test is only indicative when it works, so I wouldn't rule out a slow leak at the light just yet. Check out the following threads, beginning with the first one, an overview of leak detection.

    pool-school/leak_detection

    from-where-is-my-pool-leaking-t10295.html
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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  5. #5
    Senior Member TimS's Avatar
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    Re: Slow Leak - Just Ignore?

    Quote Originally Posted by tcpiii
    I do have one spot in the vinyl which is scratched - perhaps from when the brush broke off the pole while one of my sons was sweeping. That's about 6' deep, and I haven't figured out how to do a dye test there. If anyone can point me to a thread that discusses how to test deep leaks like that, I'd be appreciative.
    I struggled with a leak in my pool for quite a while last summer. I used an oral syringe (the kind you get at the pharmacy for giving liquid oral medications like amoxicyllan (sp?) to kids) filled with red food coloring. To fill it, I'd pull the plunger out, hold my finger over the outlet hole, pour the dye in, and put the plunger back. Then I'd swim to the bottom disturbing the water as little as possible and slowly squirt the dye where I wanted to check. On a couple of occasions, I even pulled out my scuba gear so I could just stay on the bottom

    Unfortunately, I never did manage to find the leak. I just wasn't leaking fast enough to actually draw the dye in. I would have had to be right on top of it, and though I tried to hit every area of the pool I probably missed a few.

    In your case, since you have a very specific target, you might get lucky, although 25 gallons a day is a pretty slow leak. Mine was 100 gallons a day, and I couldn't find it.

    Good luck,
    Tim.
    24' AG Round (vinyl replaced 0909) - 13500 gal - Sand Dollar Filter (150lb) - Dynamo DYNII-N1-1 1HP - Hayward HP380 Heat Pump - TF-100.
    Central Missouri

    Before I speak, I have something important to say.

  6. #6
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    Re: Slow Leak - Just Ignore?

    Well, now I no longer have a slow leak. I opened the pool Monday after I posted here. Since then I have been losing water at a much faster rate - about 400 gallons/day over and above evaporation. However, what's strange is that with the pump off and the skimmer plugged - so basically the same environment as before I opened the pool - I'm losing water at virtually the same rapid rate as when the pump is running and the skimmer open (prior to opening I was losing only about 25 gallons/day).

    Thanks for the references above. I re-tested using food coloring and still could detect nothing. My suspicions still focus on the line from the bottom drain - perhaps over the winter something settled in the hole in the pvc, which was dislodged when I started the pump, leading to a faster leak. So I need to plug the bottom drain.

    But that's the problem. My water is 56 degrees, I have no wet suit, and I can't find the spare pieces of liner that used to be in my garage. Any suggestions for how to plug that bottom drain?

    BTW, there are some minor leaks in the plumbing around the pump and filter. But, as stated above, these make no noticeable difference in the rate of water loss in the pool. I'll deal with them after fixing this major leak.
    22,000 gal, IG vinyl, 3/4 hp pump, 300lb sand filter (switched from DE), converted from baquacil (thanks to Ben), BBB since 2004

  7. #7
    Senior Member TimS's Avatar
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    Re: Slow Leak - Just Ignore?

    I suppose it depends on how big the drain is. Part of a shower curtain maybe? One of those flat, rubber drain covers used to plug sink drains where a normal plug won't work? This assumes that there is a cover over the drain, and whatever you use won't get sucked in.

    Here's an idea that might save you from getting into the water: Turn the pump off. Using the shower curtain or liner idea (or other sufficiently flexible material) Fold it over the end of your brush and quickly push it down over the drain in one fluid ( ) motion. Once it's in place, and you stop moving it, it should settle down over the drain, (assuming a flat drain) and you can lift your brush carefully back out. Turn the pump back on. The downside is that if it doesn't work as planned, you'll drop whatever you're using in the bottom of the pool, and have no good way of getting it out without getting in.

    It's just a suggestion, and it might not work, but it's the kind of thing I'd try
    24' AG Round (vinyl replaced 0909) - 13500 gal - Sand Dollar Filter (150lb) - Dynamo DYNII-N1-1 1HP - Hayward HP380 Heat Pump - TF-100.
    Central Missouri

    Before I speak, I have something important to say.

  8. #8
    Senior Member TimS's Avatar
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    Re: Slow Leak - Just Ignore?

    Another idea: Charlotte should have a few SCUBA shops that will rent you a wet suit for a fairly reasonable price. You don't need a certification for the wet suit so they should rent to just about anyone. Go rent a 7mm suit with a hood and gloves (believe me, at 55 degrees you'll want both.)

    Since the suit is bouyant, you'll also need something for weight, I'd suggest something you can hold in one hand, NOT a true weight belt unless you're SCUBA certified. Too much weight, and you're stuck to the bottom with no way up, unless you know how to dump weight under water. Be sure that whatever you use won't damage to liner. I'd also tie a rope to it in case you need to drop it. You could then use the rope to pull it back out after you're safely on the deck again.

    Even so, be advised that when you first get in, you will get a shock because the suit will fill with that very cold water (that's why it's called a "wet suit") but that water will warm up pretty quickly and keep you much warmer than you'd be otherwise. Then you will have a little time to do whatever you need to on the bottom.

    I can't emphasize enough the importance of NOT tying the weight to you!

    Also, 400 gallons a day is quite a bit, and you might want to try the dye test again. You might be getting a strong enough current to detect it now. (Keep in mind that I never found my 100 gallon / day leak, since the water didn't move fast enough to pull the dye any distance. Even the currents caused by the sun shining on one side of the pool were enough to overpower any distinct water flow to the leak.)

    Good luck
    24' AG Round (vinyl replaced 0909) - 13500 gal - Sand Dollar Filter (150lb) - Dynamo DYNII-N1-1 1HP - Hayward HP380 Heat Pump - TF-100.
    Central Missouri

    Before I speak, I have something important to say.

  9. #9
    Senior Member X-PertPool's Avatar
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    Re: Slow Leak - Just Ignore?

    dye test the steps, light niche.
    plug skimmer and returns and dye test around them.
    plug the main drain if you can.

    if you can't find anything this way then you probably have a small hole in the vinyl, and for such a slow leak you'll probably need an electronic leak detection.
    -Kevin
    X-Pert Pool Service
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    22,000 gal / 16' x 32' / Vinyl / Hayward s244t /Pentair SuperFlo 1 hp

  10. #10
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    Re: Slow Leak - Just Ignore?

    I've put a contraption together that should seal the bottom drain - I was able to get it in place without getting in the water - removing it may be more problematical. In any event, I'll have more information in the morning. Thanks for your help.
    22,000 gal, IG vinyl, 3/4 hp pump, 300lb sand filter (switched from DE), converted from baquacil (thanks to Ben), BBB since 2004

  11. #11
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    Re: Slow Leak - now a fast leak: How to detect?

    OK, a long delayed update. Boy is this a strange leak.

    Back at the time of my last post, I thought I had successfully sealed the bottom drain. The leak continued, at first at a seemingly slower rate.

    About a week later I went out of town for 4 days, and measured the water level prior to leaving. I came back - and found that I had lost no water during that time. The change in the pool level was identical to the change in the bucket. And so it continued for 2 months. No leaking whatsoever.

    Then about 2 weeks ago the slow leaking started again. Suddenly, in the last two days, the rate of leaking increased dramatically, to the fastest it has ever been: now about 800 gallons/day.

    It would seem the dye test would now be able to pick up water flow. So today I tested both with dye and then with food-coloring enhanced corn syrup. Nothing. Nada. The colors just site there by the skimmer, by the drains, by the inlets, by my little scratch in the liner.

    The bottom drain is most difficult to test. But even there we could see the green corn syrup just sit beside the drain doing nothing. Meanwhile my water level decreased 3mm in an hour.

    So many puzzles: How could this leak just stop for 2 months? I thought initially that indicated one of the suction side returns was leaking - that something had been pulled into the cracked piping sealing it, but eventually that was pulled through and the hole was exposed once again. But I know for sure the problem is not in the skimmer return, and I'm very confident there is no dye/corn syrup being pulled into the side suction. That leaves the bottom drain - but as I said, we could detect no movement of water around it.

    Thanks for any help or advice you all can give.
    22,000 gal, IG vinyl, 3/4 hp pump, 300lb sand filter (switched from DE), converted from baquacil (thanks to Ben), BBB since 2004

  12. #12
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    Re: Slow Leak - Just Ignore?

    What type pipe do have?
    Luv& Luk
    -Ted

    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!)

  13. #13
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    Re: Slow Leak - Just Ignore?

    Quote Originally Posted by waste
    What type pipe do have?
    PVC
    22,000 gal, IG vinyl, 3/4 hp pump, 300lb sand filter (switched from DE), converted from baquacil (thanks to Ben), BBB since 2004

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