IG Floating Vinyl Liner

[Tillysaint]

Thanks for the advice.

I did let the pool heal itself. In some places I helped (nursed) it along with a squeegee. It took several hours but I have no creases.

The pool installer told me there shouldn't be a problem with my pool if I removed some of the liner & inserted a cut-off hose into it to pump water. Although I trust this guy (has installed many pools over the last 20 years), I didn’t need to do it. He was going to come to my house if the pool ’t heal itself.

Here is some additional information about my pool. My pool is a diving one, 8.5 feet deep, 16 X36 feet rectangle, & installed in 1990. It has vertical walls on all sides including sloped areas in the deep end. The walls are steel and the sloped areas & bottom were done with pool cement. There’s only foam under the steps in the shallow part of the pool. I was there when the pool was installed. They had to “carve” sections of the bottom of the pool into bed rock.

Two years ago I replaced my original liner (good shape but bleached) with one that is a little thicker. When they removed the original liner, we all were surprised how well the pool looked underneath! No repairs were needed. The person who originally installed the pool also did the new liner and advised me with this problem.

The vinyl liner had lifted in spots in every section (floor & sides). The worst area was the slopping side under the dividing board, a section about 12 feet long 2 feet wide. I would’ve probably attacked this side first with the pump but it corrected itself. The other sections varied but much smaller than the one under the dividing board.

Based upon previous advice I received from the installer, I only let the pool fill up to & near the liner track & then dump the water. He told me that water can get behind the liner if you let it overflow.

I normally don’t have problems with the liner lifting since I believe the drainage is pretty good. Who knows what happens with the water table but we’ve been in a drought for the last 3 years. My pool guy told me that the new liners, although you can get them thicker, are not as good as the old ones since they’re made with a different formula.

We’re currently waiting for Hanna. Is there a way I can prevent the liner from lifting with this one? Thanks

[Vinyl_Guy]

We’re currently waiting for Hanna. Is there a way I can prevent the liner from lifting with this one? Thanks

Well that wasn't too bad, and it sounds like you have a good tech to work with.

You could as soon as you see any "bloating" install pumps as you described. But use a discharge hose that's long and towards the natural drainage of the property. Otherwise sometimes the water just finds it's way back to where it was pumped from.

[Tillysaint]

I had a few notes & discussions about water getting behind the liner if you let the pool overflow past the track where the liner is attached to the pool.

Apparently some people are under the impression that you could let a pool overflow since the more water in the pool the less likely the liner will float. I was told not to let the pool overflow.

Any comments?

Perhaps there's not a definitive answer to this question since all the people I've talked to haven't had a situation where they had to let a liner pool overflow. With all the tropical depressions & hurricanes around lately, it's been possible to get 6-8" of rain overnight. Of course, with a power failure you might not have a choice since you can't dump water out of the pool.

[Vinyl_Guy]

I don't think it's ever good to let the water over flow in an IG vinyl.

Some coping and accompanying deck systems are nearly watertight, some are not. Even if it is water tight, if you've got a small apron of deck around the pool of about 4 feet, the water overflowing out of the pool might just find it's way behind the walls, and eventually under the liner. So you could be shedding the volume of water that falls onto the pool behind the walls and eventually under the liner.

If water gets behind a liner, the most water in the pool is usually best because it prevents the bloating behind the liner to increase to its maximum. Draining a pool for instance to relieve the pressure on the wall (form the water in the pool), to insert a siphoning hose behind the liner, might actually cause more harm then good.

Think of the weight of the water in the pool, it's enormous. Then think of how much pressure is being exerted to push that weight upward. Any less weight on top of the liner only increases the chances of the liner becoming even more displaced.

Ideally you'd want the most water in the pool possible with out overflowing. Not an easy task when you'll be getting 6-8 inches of rain fall. If you going to drain the excess water out of the pool, discharge it to a location that's well away from the pool. At least then the water getting behind the liner is only the water falling where you can't control it. Namely on the deck and the surrounding ground. If the rain fall exceeds what those areas can safely drain away from the the pools in ground profile, there's not really a lot you can do about it. You just don't want to add to that by discharging water that fell in the area of the pools dimensions. When a pool overflows it's the same as the roof on you house. Your adding a volume of water from a larger area, to a much smaller one. You don't want to do that especially when the smaller area is already saturated.

It's a tough balancing act. When installing pools with a ground water problem, I've had to go sometimes 100's of feet with the discharge before it wasn't just cycling back into the pumps at the bottom of the pool.

There is of course the option (sometimes a must with gunite or solid bodied pools) of installing a Hydrostatic Relief Valve in a main drain. A Hydrostatic Relief Valve is a simple device. It's an opening to the area below the liner in the form of a threaded fitting in your main drain. On top of the fitting is a cap with an o-ring that seals it, and a spring to pull the cap down tight and keep it in place. Between the spring and the water in the pool the cap stays water tight. But, if the water pressure coming form the bottom of the pool exceeds the the pressure of the water in the pool, the cap lifts up and releases water into the pool from below the liner.

Hydrostatic Relief Valve

Although installing one post construction without the the proper preparation greatly reduces their effectiveness. Ideally if a water "problem" may be persistent in an in ground vinyl liner pool, stone can be placed to direct underground water towards the Hydrostatic Relief Valve. That stone has to be placed during the construction, and before any hard bottom is troweled.

They're often installed in gunite pools if there's any chance of a ground water problem. If not a gunite can pop itself clear out of the ground by several inches snapping any fittings directly hard piped into the body. I've seen this happen, it's not a pretty sight and a huge repair cost, sometimes costing more then a new pool since the old shell has to be extracted most of the time.

[Tillysaint]

Thanks for the responses.

I understand to not let a pool overflow. However, there are a couple of inches above the liner attachment track before the pool overflows.

If you let the pool fill above the track but not overflow, is there a problem of water getting behind the liner through the track and causing the liner to float negating the advantage of having the extra water in the pool? In other words, do not let the water get above the track?

In my pool I would gain about 2 inches of area above the track while I have about 6.5 inches from the middle of the skimmer to track. In my latest situation the water was maybe a .25 inch below the track after the rain!

[Vinyl_Guy]

Thanks for the responses.

I understand to not let a pool overflow. However, there are a couple of inches above the liner attachment track before the pool overflows.

If you let the pool fill above the track but not overflow, is there a problem of water getting behind the liner through the track and causing the liner to float negating the advantage of having the extra water in the pool? In other words, do not let the water get above the track?

In my pool I would gain about 2 inches of area above the track while I have about 6.5 inches from the middle of the skimmer to track. In my latest situation the water was maybe a .25 inch below the track after the rain!

I don't think water that finds it way behind the liner via the track would cause problems, other then what the moisture might do, effecting the foam or the walls (if they are wood for example).

It's the pressure of the ground water rising up and under the wall then behind the liner that normally causes it to lift out of the track.

But to be on the safe side I'd keep it below the track. The extra few inches isn't going to make all the much difference. The pressure at the top most point of the pool's water isn't all that much.

If ground water has made it far enough to lift the liner up and out of the track, I don't' think the extra few inches above the track are going to stop it at that point.