slow leak IG vinyl liner pool

[hannadock]

I have a 20X40 IG vinyl liner pool. I noticed when we closed last winter the water level was below the skimmer but thought I had just pumped too much water out. I took cover off and found I only had around 2' of water in pool. I filled it up to about 4 feet but has drained down 14" now in 3 days. Tried dye but not luck. It is a very slow leak. This liner is only 4 years old. Any advice on how to find this leak.

[Poconos]

I know that sinking feeling. In 72 hours, 14" of water computes to 97 gallons per hour which is a substantial leak. Mine was just around 50 and I found it easily with dye, patience, the right technique, and knowing what to look for. There are a lot of threads in this particular forum addressing leak detection and repair. I'll look up some threads and just wanted to post this so you know the post has been seen. Check back shortly...like an hour.
A question...is there a deep end and how deep?
A very common leak area is where the liner is pinched for a seal around the stairs or, as in my case, where the liner transitions from bottom to wall. Something else to do is to start measuring the leak rate over time. Use a ruler or something to measure the water level referencing some fixed point like a spot on the stairs or the pool bottom at a specific point. Measure every few hours. The rate at which the leak is occurring can be an indication of how deep to look. As the water level approaches the leak point the rate will slow and eventually stop. In my case the leak was at the deep end and never slowed.
I will be back...
Al

[Poconos]

Check this thread.

http://www.poolforum.com/pf2/showthread.php?t=101

My posts in this thread are pretty detailed. The garden sprayer I'm talking about is a small 1 gallon pump type found at a Home Depot or equivalent for about $20. I used black vinyl electrical tape and silicone seal to jury rig the vacuum line hose to the sprayer nozzle. As Elmer Fudd says...you have to be vewy vewy quiet... when squirting the dye. Any small disturbance in the water can make it difficult to see the leak. You should have no problem with the size of your leak. The trick I found is you have to give small squirts of dye. If you try and fog an area you can miss the leak. The dye cloud has to be within a few inches of the leak to see the dye being sucked. I would position the pole and hose very slowly, wait an additional 30 seconds or so and squirt some dye. Very tedious process. During the experimentation phase I even found that the sun warming the surface of the water set up some deep currents that made it more difficult to see the dye suck. Luckily I had a good flowing stream for fill water so I didn't have a time constraint.
Post #9 has pics of the patch method and a pretty detailed description of the process. The patch has now been in place for 2 years and shows no signs of peeling.
Something else my pool guy told me is that typically if a liner seam lets go it will do it in the first couple years. I still have no idea what caused my cuts but it may have been something on the pool bottom that cut it when I was brushing.
Hope you find it and I'll be keeping an eye on this thread.
Al (ajs-1)

[JohnT]

Al has given you excellent advice on finding a liner or pool shell leak, but don't ignore the plumbing. For the water to drop to 2ft, the leak would have to be in the hopper end of the pool (assuming a diving pool) or in the main drain plumbing near the bottom.

[Poconos]

I tend for forget about main drains. I don't have one and never would have one. John is absolutely right. The drain is another high probability area to look at.
Al