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Thread: Leak help

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    Leak help

    We have a gunnite pool, and it has dropped about 1.5' per day of water for the past few days. I had lowered the water level and winterized the pool and went out the next day to put the winter cover on and the pool was down 1'. We had to leave for the weekend and when we came back the pool is down about 3' and falling. I am not sure how the leak happened, but it must be in the main drain (in the 9' deep end) as the water level is below everything else. It is an older pool, probably 20-25 years old. I have a number of questions.

    1. Should I fix this now and fill it back up with water or wait till spring? Fixing now presents some challenges as the leaves are falling and the water isn't clear.
    2. If I should fix it now, should I pump out the rest of the water and fix it dry?
    3. How should I fix it? Cap the main drain? As I mentioned, it is 9' down.
    4. What are the dangers (to the pool) of leaving it, or fixing it dry, etc?

    Thanks for any help and if you think of answers to questions I haven't thought of, I am open to any and all input.
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

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    JasonLion's Avatar
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    Welcome to TFP.

    With a plaster pool you don't have to fix it right now. One risk for a plaster pool is that the water table will rise and float the pool out of the ground. However, if you have a significant leak, water table water will be able to get into the pool and equalize the pressure, preventing the pool from floating. There is still some risk, since there is a small chance that something could somehow block the leak while the water table rose, but that is comparatively unlikely, particuarly with a large leak. Another issue is preventing water from getting into the main drain and freezing, causing additional damage. If you are going to be sealing up the main drain that is not really an issue, but if it can be repaired you don't want additional damage.

    If the problem is around the main drain you might get lucky and find an obvious crack or leak somewhere in the area of the drain fitting. Otherwise you either plug the entire main drain or tunnel under the pool to get to it from below.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. Back To Top    #3

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    One thing I can do to minimize water/freeze which is a concern here in Michigan is to fill it with antifreeze when it gets low enough. If the water is out, and the weather is decent should I go ahead and try to fix it? We are getting into colder weather, but not real hard for a few weeks. I marked it this morning and it has already lost a couple inches yet today. I could pump all the water out to make it accessible this time of year, especially if it is all going to leak out anyway. Thoughts? Thanks for the response.

    I was over at poolforum, mostly a lurker (but learned a lot), and sometime poster and decided to come over here with everything happening there. Thanks for the welcome.
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

  4. Back To Top    #4

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    Guitbusy, welcome to TFP!

    Do you by chance know if there is a 'hydrostatic valve' in the MD? The hydrostat lets ground water into the pool rather than the force of the water popping the pool out of the ground, sometimes they will let a little water into the pool and some sand or debris will get on the gasket and keep them from fully resealing, thereby allowing water to drain from the pool.

    I don't recommend, diving down to check it at this time of year (at least without a dry-suit and scuba gear). If you are comfortable with draining the water and don't have any issues with the fill water, you may do well to drain the pool and check out the MD. Inspect it for obvious cracks, check the hydrostat (if applicable) and plug the line (if you can pressure test the line that would be GREAT, but just plugging it for the winter would prevent any water loss from a broken line).

    If I've gone 'too fast' for you, simply ask for whatever details you need from me. I hope that you can get this solved soon so that it's not a constant worry over the winter
    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!)

  5. Back To Top    #5

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    Thanks again for the welcome. I don't know if there is a hydrostatic valve, but I am comfortable draining the water so that is what I will do. I probably won't get to it until Thursday at the earliest. I will drain it and let you know what I find. I am not exactly sure how to pressure test it, but I can search the forum and find out. I think I can do it once I know what it is I would like to get it taken care of so it isn't a concern over the winter that is for sure. It is really strange how it just started happening when I was closing the pool. It must have just been its time. Thanks for all the help and quick responses.
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

  6. Back To Top    #6

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    Too funny. I search pressure test, and the above post comes up first. Anyone have pointers to a thread on pressure testing?
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

  7. Back To Top    #7
    JasonLion's Avatar
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    To pressure test the plumbing you need to seal up all of the entrances and exits from the plumbing and then pressurize it with air, wait a while, and check to see if the pressure is holding. This can be done on the entire system or, if you have valves on each pipe run, it can be done on the individual runs. It requires some equipment, mostly plugs for the ends of the pipe, an air pump (usually a bicycle pump), some kind of fitting that allows you to connect the air pump to the pipe (typically a winterizing plug with a bicycle tire stem valve attached to it), and a pressure gauge (you can usually use the one on the filter).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  8. Back To Top    #8

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    So this would help in my case tell me if the leak was in the pipe, or in the area around the main drain. I got it, thanks. I am going to drop the water out, check the main drain and try to pressurize the tubing. I will let you know from there what I find out. I may end up just capping and filling for the winter but will see what I come up with. Thanks.
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

  9. Back To Top    #9

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    Ok, here we go. I have some updates. I am down to the main drain. Here are some pictures and then I will give my theory and see what you folks think.





    Ok, #1 is the suction line back to the pump, and #2 appears to be the pressure valve that ensures the pool doesn't float due to water pressure in the surrounding ground. #2 has a very weak spring and a very bad/old seal. When I took the water out of the main drain, the pink RV anti-freeze that I had put in, at the pump end came rushing into the main drain. This tells me (I believe) that the leak had to be in the pressure valve. I would have expected that the anti-freeze would have leaked out if it was in the line versus in the pressure valve. Anyone have any thoughts on this? Also should I be able to take this valve to a local pool store and get a new one? My thought is to replace the valve and add some water to see if the water leaked out. Thanks for all the help, I believe I am almost done on this one, just want to check my sanity.
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

  10. Back To Top    #10

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    duraleigh's Avatar
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    I've been lurking on this thread because I have no main drain or hydrostatic valve.....just learning.

    Those are VERY descriptive pics you posted.....nice computer work. Secondly, your plan (and cure) makes good sense to me but I don't have enough prior experience to be definitive.

    It sure seems like the valve "let go" but I wonder what caused it in the first place?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  11. Back To Top    #11

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    Thanks, I have found that a picture definitely says a lot more than I can. The cause is probably age and the act of winterizing it. The pool is over 20 years old, and I have been slowly replacing the infrastructure over the last 4 years. The seal on that valve comes off on your hands like black ink. It is also misshapen and weak.
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

  12. Back To Top    #12

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    Ah Ha! The hydrostat seems to be the weak link here! With the antifreeze coming back in as you drained, any MD line leak would have to be above where the antifreeze was. If memory serves , the part number may be SP 1056, but it should be imprinted on the old valve, any pool store should have or be able to get you one. Wrap the threads with teflon tape before installing the new one and put some silicon or teflon based lube on the new o-ring.

    Also follow the advice on the other thread if you plan to use the pond water to refill the pool!

    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. Back To Top    #13

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    Found a new valve after calling around to some local pool places. I replaced it yesterday and added a little water. So far the water has sat for over 12 hrs without any leak. I think I have that part fixed, now I just have to fill it...
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

  14. Back To Top    #14

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    alright, have had about 1 1/2 feet of water for over 24hrs. I think I have the issue fixed for good, and now I am on to filling the pool with pond water... I will take a picture of the contraption I made to attach to my sprinkler pump to fill my pool with. It is made with pvc and has 3 hose connections to run 3 hoses into the pool. Might help someone else.
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

  15. Back To Top    #15

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    Pool is full of water back up under the returns, and has stayed that way for a few days. I need to get my cover on now, as leaves are falling. Hooray. All for a $12 part
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

  16. Back To Top    #16

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    Glad it's all set!!! Have a good winter without having to worry if there will be water in the pool when you open it!
    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!)

  17. Back To Top    #17

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    Thanks for the help!!!
    16x36 Inground Gunite
    25-30,000 gallons
    4' - 9' deep end
    Chlorine/Bleach

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