Fiberglass pool leak

[al27]

I have an inground fiberglass pool that has been leaking for approximately 2 months now. When I first discovered the leak, it was leaking 1 1/2 inches a day with the pump on and an 1 inch a day with the pump off. None of the pool services in my town have the equipment available to pinpoint the leak, so I paid American Leak Detection $600 to do a pressure test and test the shell of the pool. I was told that the only leak found was a leak in the light niche which was repaired using some pool putty. It is now leaking only 1/4 inch a day with the pump off and 1 inch a day with the pump on (after accounting for evaporation). My local pool company came out and tested the light niche with some dye and they didn't see any areas in the light niche that were still leaking. They think there is a pressure-side leak that was missed by American Leak Detection since it is leaking more with the pump on than with the pump off. After dye testing the returns, they think it might be caused by a cracked fitting in the return behind the pool wall. If this is true, I don't understand why American Leak Detection's pressure test was normal. Would the pressure test show a leak caused by a cracked fitting in the return if this problem exists? I also don't understand why my pool leaked 1/4" in 24 hours after the pool company plugged the returns if the cause of my leak is a cracked fitting like they think it is. (If water can't get in there when it is plugged, why did it leak the same amount as it always does with the pump off?) I didn't lose any water to evaporation when I did my bucket tests so it looks like it is leaking 1/4" without the pump on, even when the returns are plugged.

I'm very frustrated because I've already spent over $1000 on diagnostic services for this leak and i still don't know for certain exactly where is it leaking. Since fixing this problem might require demolition of my concrete deck, I want to make sure I know for certain where it is leaking before any repairs are made. American Leak Detection is the only company in my area that has the necessary equipment to tell me for sure where the leak is and they will charge me $600 more to come back out here to pinpoint the leak again since I live two hours away. If anyone has experienced a leak like this before in their fiberglass pool or has any suggestions on what could be causing it, please post.

 

[OTPirate]

Does the leak detection company have any kind of guarantee? It sounds like you know some of the ways one can determine where a leak is: Pool School - Leak Detection Leaks can be very frustrating.

 

[Awilli8203]

I had a leak in my fiberglasspool when first installed that was hard to find and it ended up to be a leak where the skimmer fitted to the fiberglass shell right where the skimmer door is. They calked the joint there and it has been fine since. It might be a good idea to checck there and calk any seam you see

 

[al27]

Thanks for the replies. My local pool company finally came out and pressure tested my pool and found that the return line would not hold pressure. They think that it is caused by a cracked fitting in the return behind the pool wall like their dye test indicated. It looks like they are going to have to cut into my concrete deck in order to repair this so I'm not too happy to hear this news. American Leak Detection agreed to come back out here to tell me the exact location of the leak since they missed it the first time. I'm going to make sure they do a more thorough job checking the shell of the pool this time since I'm still losing some water when the pump is off. They apparently have a 30 day guarantee so it looks like I won't be charged another $600.