Small crease in vinyl liner in in-ground pool

[Samiam]

I have a 20 x 40 inground pool with vinyl liner. The pool (and liner) is five years old. I recently noticed a small crease in the shallow end that is about six inches long and raised about 1/4 of an inch. What should I do? How do I know if it's caused by a leak (NO!!!!!!!!) or if something else could cause it. The liner seems in good shape. There is some discoloration where the sun continually shines on the part that is not in the water, but other than that, all is well. I've noticed a few "divots" in the concrete under the liner in some areas, too. Is that normal? I'm almost afraid to ask for fear someone will tell me bad things! We are in Iowa, so the pool is subjected to crazy weather, but the pool balance is usually good, except recently I had trouble getting the pH up to where it should be. Break any bad news to me gently...thank you. Sheila

 

[mickey4paws]

Hi Sheila and welcome to TFP
I'm very interested in your question as I have the same problem. I think maybe my crease has been there for a long time but I'm not sure. Do you know how long you've had your crease?

 

[Samiam]

Thank you. I've watched this forum for a few weeks, and decided to be an active participant rather than an observer :-D My crease is new this summer. I vacuum the pool regularly, and the liner is a very light color, so it's easy to notice any changes, and this change is definitely recent. It wouldn't appear that there is a leak (which perhaps with an in-ground pool, there is never leaking...you can see my lack of knowledge here!) because the water level doesn't change more than through regular evaporation.

 

[Molson]

Welcome to TFP!

I have a few creases in mine also, though the liner is 20 years old. I just watch when I'm vacuuming not to whack the crease. I don't know what causes it, but I haven't noticed any adverse effects.

 

[Samiam]

In some earlier posts, I noticed that the moderators have said the creases could be because of water underneath, which sounds ominous, but I'm hoping there is some other innocuous cause that is merely cosmetic. How often do vinyl liners have to be replaced, on average? I'm in the Midwest, and the pool is only open from April through October.

 

[gkruske]

I have a vinyl liner, as well, and when we opened it for the first time after we bought the house, PB kind of schooled me on vinyl liners. Ours is probably 4-5 years old currently.

He said we will noticed irregularities from time to time. Small divots are normal. However, if those divots become larger, or deeper, over time, then you will have a problem. Sand bed is shifting underneath. In some cases, they are able to fix without removing liner. I have a divot that was probably there before we bought the house, and was victim to undiluted granular shock. Shock settled in that divot, and is now bleached white.

Only other thing he mentioned to watch out for is the liner coming loose from the track. Watch for it coming loose in large portions, or if the opening is starting to collect water. The collection of water will produce the same symptoms as the divots.....it will start to shift the sand bed.

I'm no expert here....just mentioning what was told to me as a complete novice.

Guys in the industry might have better advice than I.

Greg

 

[Samiam]

Thank you, Greg. Isn't the sand bed underneath the concrete? I absolutely don't know anything and remember even less about watching them build the pool, but I thought the liner was directly over the concrete...can you or someone educate me?

 

[duraleigh]

Most vinyl liner pools have a floor of either sand or cement and vermiculite.

They are usually pretty soft and, with the pool light on at night, may well look like the surface of the moon. They're very easy to dent just by jumping in.

It is also pretty common to have small wrinkles to some degree in a vinyl pool. It may have been there all along and you just now noticed it.

It's not particualry common for wrinkles to suddenly appear and, if that's the case, it certainly means you should keep an eye on it. As small as it is, I doubt it's a big deal.

 

[gkruske]

duraleigh is correct. If I turn my light on, the bottom of my pool looks like a lumpy sack of potatoes.

I just keep my eye on the bottom....I have steel walls, so in those spots, I would look for bulging in the bottom, where water may be getting trapped. If the Kreepy Krauly ever starts to get tripped up in the middle of the pool, then I know I'll have something to deal with.

My take on it is that vinyl liners have to be replaced every 8-10 years or so, under normal conditions. If it's lumpy down there, fine. As long as it's not leaking anywhere. PB will apply new sand and smooth it out again when replacing the liner.

Greg

 

[mickey4paws]

Lots of great answers here, thanks. It sounds like we don't really have to worry about the crease, Sheila. I think mine has probably been there for a while (liner is 6 years old) but I never noticed it before because we were using Baquacil (cloudy all the time). That's one thing about having a nice clear pool now, I notice all the imperfections.

The bottom of my pool seems pretty solid so I wonder if the PB used vermiculite instead of just sand. I'll have to look at my receipt because I can't remember what he used. He did install a shallow end at the time and the crease is on the ramp part going into the deep end.

I hope my liner lasts as long as Molson's!

 

[Samiam]

Thank you so much Dave, Greg, Molson and Mickey4paws! I will just keep an eye on it and ask the Pool Guys at closing to look at it, too. This forum is great! I've never participated in anything like this before. What is the best way to test the water? Strips, digital, dropper mix thingy? Thanks.

 

[waste]

Samiam, welcome to TFP!!

Mickey4paws- does the wrinkle run ~ parallel to the transition? If it does, I'm thinking you had water trucked in to fill the pool or , at least, set the liner (though a fire hydrant could do the same thing) - I won't WAG unless you tell me my suppositions are right

A quick primer on Ig liner pools and their bottoms . Bases pros and cons:

Vermiculite

Pros:

Water passes through easily
Light and easily applied (usually*)
Not abrasive to the liner
Stable because of the cement in it

Cons:

Water passes through it easily (this lets ground water push the liner around - causing wrinkles )
Dent's fairly easily when struck by heavy object
Mixed on site, inconsistent mixes often result in the 'Moon crater' effect
Critters and roots can easily burrow through it
Regular flowing of water through it will degrade the durability


Sand

Pros:

Cheap
Easy to apply
Non abrasive to liner
Water passes through it easily

Cons:

Tends not to stay where you put it :grrrr:
Sharp rocks if not properly screened
Dents VERY easily
Critters and roots can VERY easily burrow through it
Any steady stream of water will cause a chasm to form

Sand and cement (or concrete )

Pros:

Durable (hard as a rock = very stable)
Water doesn't pass through easily
Premixed, so no inconsistent mixes
Critter and root resistant
Can use a 'screed' board to level, thereby reducing the 'Moon effect'

Cons:

Very abrasive to liners
Water doesn't easily pass through
Any ridge or a rock caught betwixt liner and bottom will damage the liner
Enough hydrostatic pressure will 'pop' up the floor
Expensive



With any of these you are at the mercy of how skilled the person applying it is!

BTW, 20 years is easily attainable for a liner pool - chemical abuse MUST be avoided

Samiam, the best way to test is with the drop based kit - Dave's tftestkit (in my sig) is as good as they come, but Taylor's 2006 - K is a decent approximation (Leslie's has their own rebranded version of it, but it's usually only available on line) :-D What you want is the "FAS/ DPD" chlorine test - that's what makes these kits preferable

Hope y'all enjoyed the read

 

[Samiam]

Ted, Thank you so much for the information. In answer to your question (or supposition), my pool was filled with a regular 'ole garden hose, but that was five years ago...we only add to every spring now (again with garden hose). I recently had a battle with too low of pH...got that conquered, now the alkalinity is a bit high, but I'm reluctant to do anything because all the other levels are good...except the cya is high, and the chlorine a bit high, but I'm sure that won't last because it never does...the first filter only lasted three years, so maybe my chemicals weren't always under control, but the water is usually clear and no signs of algae or other bad stuff.

I am thrilled to have you all as a resource. I am in a small town in the Midwest and there are very few pools, so it's difficult to find people who can help. Thank you, thank you, thank you!