Leak detection - 28K inground vinyl

[nhpoolguy]

I am losing ~1.5" per day out of my vinyl lined inground pool. It's ~28K gallons, liner is new as of two years ago.

I've heard that one can use food coloring/dye to detect leaks by squirting it around suspected leak points to see if it gets sucked in, and I have tried this without success. There were a number of holes last year around the steps that were patched, I tried this area and did not see anything amiss. Ditto for the return jets, skimmer, and main drain (I got as close as I could, ~3ft away -- but not sure how close the dye has to be to see the effect).

Two odd things about this pool...

1) Last year we had this same issue... losing tons of water later in the season although it was fine at the beginning of the year.

2) Last year and again this year we had major issues with the not being able to purge all the air out of the skimmer basket early in the year, but things seemed to work themselves out after a couple weeks.

For the latter issue we had the local pool place come out and do leak testing of the skimmer line and they did not see a problem, we skipped testing the main drain because they said we would have to pay for a diver to plug the bottom of the pool.

Possible that these two issues are related? I'm focused on the leak right now and hoping for help on that, but maybe there's a bigger picture that I'm missing?

[PoolDoc]

Dye checking like that is a matter of inches -- 1" - 3" -- not feet. You usually have to be in the pool, and it's hard to be as still as you have to be without SCUBA or a snorkel unless you can hold your breath much better than I can.

But . . . leak detection is hard, even on site. I learned the hard way to tell my customers that I had found and repaired "a leak" or "some leaks", but that we wouldn't know if those were "the leaks" for a couple of days. I also warn customers that "finding leaks" is an open ended process with no upper limit on cost.

[Poconos]

Ben is right. You need to be right at the leak point to see the dye being sucked in. Also as he said, the trick is to not have much movement. The leak test jig I made is a long piece of auto vacuum hose, skinny stuff and cheap, taped to a 10 foot length of 1/2 PVC pipe. The business end sticks out a few inches so you can position it where you want. The other end is jury rigged to the nozzle of a small garden sprayer filled with dye. You can use cheap black electrical tape to temporarily hook the hose to the nozzle, or get fancier and more permanent with silicone seal. Position the hose where you want and give just a little squirt as you move along seams or other suspect areas. For dye I use fluorescent red dye tablets that I scarfed from a chem lab where I used to work. I suspect you can get dye markers at a dive shop and make a dye juice from them. Food dye is expensive. Some people use phenol red, the pH indicator. I've never tried it but have suggested boiling raw chopped up beets and using the red liquid. Eat the beets afterwards. Finding a leak takes a lot of patience. You say the liner is only two years old so I'd look into warranty issues too.
I found a deep end leak years ago and did a lot of experimenting trying to find the best technique. Never had to get wet, even for the patch.
Al
Edit: I was told by the installer at the time that if a seam goes it will typically go in the first couple years. Mine was a lot older than that and in my case it wasn't a seam. Looked like something sharp cut some slits where the bottom transitions to the side at the deep end bowl.
(ajs-1)

[PoolDoc]

Al,

Can you send me some pictures, or post them on poolforum.pics ? That's an interesting idea, and I bet quite a few pool guys would check it out, as well as our regular users.

Ben

[CarlD]

I had a seam go 10 days after the liner was installed!

Carl

[nhpoolguy]

The water level stabilized for 24+ hours at about 1" above the bottom of the skimmer intake, so I think I have the vertical location of the leak fairly well pegged.

My wife topped it off again though, so I'm not able to do a dye check with it right at the level of the leak at the moment. I'm assuming best chance of success is if I can put the drops on the surface of the water when the leak is very close to the surface as well.

I gave it another whirl anyway, checking all seams, corners, and around the skimmer by putting drops every inch or so. No luck, despite being a dead calm day and being able to do this while outside the pool. I'll try again when the level sinks some more. Won't take long! :-)

Am I being overly optimistic to assume that if the water level stopped above the jets and above the bottom of the skimmer intake -- and given that the pump is holding its prime -- that this rules out the plumbing as a source for the leak?

[waste]

Welcome to the Forum!

If you want to eliminate the plumbing, perform a vessel test. Turn off the pump, plug ALL inlets and outlets from the pool and mark the waterline in the pool. Concurrently, partially fill a bucket with water and mark the level and set it on a step. The next morning compare the water loss in the pool to the water loss in the bucket (any water loss in the bucket is due to evaporation). If the pool losses more than the bucket, you've got a leak in the vessel/ liner. If the loss is the same, it's a plumbing/ equipment leak.

If you can do this test and report back, as to the results, we'll help you narrow down the source

[nhpoolguy]

Turn off the pump, plug ALL inlets and outlets from the pool and mark the waterline in the pool.

I'm familiar with the bucket test, but I'm not sure how I would accomplish plugging everything...

Plugging the jets is easy of course, but I'm not sure of what an effective method would be for plugging the skimmer. For the main drain I'm truly baffled. How can one plug the main drain without scuba gear? Even then -- I wouldn't know what to put there that would actually create a reliable seal.

Suggestions?

[PoolDoc]

You're right -- it takes SCUBA to plug the main drain . . . unless you are an accomplished 'free diver'.

But, you can plug everything else. Then, your test become shell + drain, instead of just shell. Lowes probably has blow up Cherne plumbing test plugs available.
http://www.cherneind.com/Pneumatic/Default.aspx

[SalemCastles]

I plugged my main drain using a mask and snorkle and flippers. I'd dive down stay upside down and with flippers be able to stay there long enough to get a few turns on the screws holding the screen on. Once removed I gained access to the threaded port and it was the same size plug as the returns. It took me ten or fifteen dives with rests in between and I made sure I had a "buddy" keeping an eye on me. Having said that I would plug the holes in the skimmer first and wait to do the drain. The fact that yours slowed down tells me it isn't in the drain. My stairs have a few cracks and it was a previous repair that had started leaking again.