Vinyl pool concrete damage

[Eastern]

My family and I moved to a home with a pool this past summer. This is our first pool and the TFP website has been an invaluable resource to us in learning our to take care of our pool!

Over the summer, we hired a pool tech to come to our property and explain how to keep up our equipment. Most of her advice jived perfectly with that given here (and she was so excited to see that we use a Taylor test kit).

One problem that she noted, and became quite obvious to us after she pointed it out, is that the concrete under our vinyl liner is very damaged. The entire floor of the pool is covered with divots and pock marks, and one section has a 1 or 2 foot wide hole that is a few inches deep. Her opinion was that the polaris robot that came with the pool is at fault. She said that she has seen this a lot, and that the movement and pressure of the wheels erodes the concrete over time. She usually suggests that owners of vinyl covered concrete pools hand vacuum.

I've searched around on the forum a bit and haven't seen this kind of complaint in any other threads. Any thoughts on whether this gal is on the right track or what could be causing the damage to our pool?

 

[JasonLion]

That is not even remotely common. Any way you look at it the concrete must be defective, otherwise the Polaris wouldn't have any effect. It might well be that one of the builders in your area uses sub-standard concrete and the Polaris pushes a little harder than other things, and thus is the immediate cause, but if the surface was properly made the Polaris would not have any effect.

 

[JohnT]

May not even be concrete under the liner. Some use sand, and many use some kind of vermiculite and cement mix that stays soft for quite a while.

But either way, if the cleaner was damaging the floor it would destroy the liner.

Is it by chance a new liner put in right before the house sold?

 

[bk406]

If there are divots and pock marks, my guess is the floor is made out of vermiculite and not concrete.

 

[Eastern]

Thanks for your replies. No the liner is original to the pool, and was not installed correctly to begin with, as it is pulling away from the rim in a few places. It sounds like the pool installer cut corners.

This gal said that she sees this alot with robots, so maybe you're right about there being a builder in hte area using poor materials and she mistakenly has assumed it was the robots.

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[bk406]

If it is vermiculite, it's not that is a poor material, it's just kind of what it does over time. Sometimes it doesn't do that, but a lot of the time it does. If you replace the liner, it isn't too hard for the pool guy to fix.

 

[Eastern]

Can the floor material be changed when the liner is replaced?

 

[JasonLion]

It is common for the floor to get re-leveled when the liner is being replaced. It would be a bit more work to change the material, a very reasonable add on project.

 

[Eastern]

Would the fact that the vermiculite in our pool is so dented after only six years indicate a soil/climate issue and that we should try another material next time, or is it more of a builder/quality issue?

 

[JasonLion]

I think of it as either a builder quality issue, or a ground water issue. Either the concrete around the vermiculite was less solid than it should have been, or there was a lot of ground water weakening it. Vermiculite in concrete is a very common bottom finish, and while some minor damage frequently occurs, what you describe is more significant than just about anything we usually hear about.

 

[Divin Dave]

To add what the others have said, vermiculite or as an alternative poolkrete if indeed that what the bottom is, .... is EXTREMELY difficult to install and get it smooth without imperfections such as you describe. Its entirely possible the installation of it wasn't done every well to begin with.

I agree, that if this abnormailty were caused by the pool cleaner, the liner would also be destroyed.

 

[n240sxguy]

For a pool cleaner to cause that kind of damage, you would need a forklift to put it in the pool. Walking in the pool exerts more pressure than the wheels on any pool cleaner.


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[Eastern]

Incidentally, we do have a lot of fading on the vinyl, but I imagine that's not the kind of damage you are talking about.

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So is there a way to ensure that this doesn't happen again, or at least not to this degree, when we replace the liner? The pool is only six years old!

 

[Divin Dave]

Sure it can be contained. The real question remains though... what caused it? If its just becaue the installation wasnt done well to begin with, which is somewhat common with vermiculite, then you can do some smoothing and patching with a few bags of poolkrete. Easy enough.

If the bottom is actually damaged to some significant degree, that could maybe be caused by a lot of ground water under it (high water table), or poor preparation of the pool bottom prior to installation of the vermiculite.

Ground water can be resolved by a sump pump installed under the pool or by a Well spikes strategically located around the deep end. I doubt this is the problem though)

If the bottom was poorly prepared to begin with, then it may be possible just to patch the vermiculite, or at worse case, remove it and completely re-work the bottom.

As you might imagine, there is no real way to know what the situation will be until the liner is taken out.

 

[Eastern]

Thank you. I hope I can find a quality installer when the time comes!