Auto Cover causing deck pitting

[linck]

Our fiberglass pool (14,000 gallon Latham Cancun) was installed summer 2021 with a Pentair Intellichlor SWG and VS Pentair pump. We have loved it. It is so easy to maintain correct levels, only adding muriatic acid to keep the pH level down weekly. We leave the pump running 24/7 and did not close the pool up for the winter.

We also have an auto cover and over the December and January of this year we had it closed. We opened it a week ago and saw three separate areas of the stamped/stained concrete pitting. The PB said it was caused from the saltwater sitting on it under the cover. We had heavy snow/ice which was added pressure on the cover touching the concrete. The concrete was done in July and was sealed. Now he says we will have to switch to chlorine to avoid any continued damage to the concrete and will install an inline chlorine dispenser. This is disheartening since I have concerns with how easy this will be to maintain compared to the SWG and rising levels of CYA using pucks. I was looking at ozone generators to help with using less chlorine. Any insight as to the issue with the concrete (which they are going to fix but I am not certain how) and with opinions/insight/tips on a maintaining chlorine pool with an inline chlorine dispenser?

Thanks!

 

[an1vrsy]

Welcome to TFP! Sorry you are facing this dilemma with your new pool. I am a fellow pool owner with an auto-cover. However, my auto-cover is for a rectangular shaped pool so doesn't cover anything except water. In my opinion, which really won't change your PB opinion, the salt content in your pool water is not the culprit. Have you tested the salt content with the Taylor K-1766 test? Do you know the salt ppm level? I am sure more experienced eyes will be commenting on this post shortly.

 

[an1vrsy]

Oh, is the photo you posted of the pitting the same across all of your decking? Or just one specific area?

 

[ajw22]

Are you using dry acid or muriatic acid to lower pH?

 

[linck]

Oh, is the photo you posted of the pitting the same across all of your decking? Or just one specific area?

It is in three different areas. One near the skimmer, one by there you can see the robot in the water, and one on the curve where the covered tabled is.

Oh, is the photo you posted of the pitting the same across all of your decking? Or just one specific area?

 

[linck]

Welcome to TFP! Sorry you are facing this dilemma with your new pool. I am a fellow pool owner with an auto-cover. However, my auto-cover is for a rectangular shaped pool so doesn't cover anything except water. In my opinion, which really won't change your PB opinion, the salt content in your pool water is not the culprit. Have you tested the salt content with the Taylor K-1766 test? Do you know the salt ppm level? I am sure more experienced eyes will be commenting on this post shortly.

I have not tested the salt level lately but we have only added one bag in late August or early September after the initial start up when the SWG said it was low and the reading was low.

 

[linck]

Welcome to TFP! Sorry you are facing this dilemma with your new pool. I am a fellow pool owner with an auto-cover. However, my auto-cover is for a rectangular shaped pool so doesn't cover anything except water. In my opinion, which really won't change your PB opinion, the salt content in your pool water is not the culprit. Have you tested the salt content with the Taylor K-1766 test? Do you know the salt ppm level? I am sure more experienced eyes will be commenting on this post shortly.

Yeah, if I had known this was going to be an issue with this shape pool/cover, I would have gone with rectangle for sure. I will check the salt level tomorrow but it has never been high.

 

[linck]

Are you using dry acid or muriatic acid to lower pH?

Muriatic acid but it was in check when we closed it. Do you think a high pH could've caused that since we leave the pump running even with the cover on?

 

[ajw22]

Muriatic acid but it was in check when we closed it. Do you think a high pH could've caused that since we leave the pump running even with the cover on?

No, I was thinking about sulfates from dry acid damages concrete.

 

[mknauss]

I assume the cover is sitting on the concrete.

How would the pool water effect that? Specifically the salt in the pool water.

I suspect the cover sitting on top of the concrete traps moisture. That moisture draws out the minerals in the concrete, which is called effloresence. I suspect the sealant on the concrete is mostly worn away by the cover sitting on the concrete.

This has nothing to do with salt in your pool water. All pool water, unless chlorinated with chlorine gas or calcium hypochlorite, has salt in it.

 

[an1vrsy]

Now he says we will have to switch to chlorine to avoid any continued damage to the concrete and will install an inline chlorine dispenser.

With the more experienced eyes viewing and posting on this thread, their responses are way better than the PB. This is your pool, I would not allow the PB to remove/replace the SWG with an inline tablet feeder. Long term use of tablets introduces small amounts of salt and increases cyanuric acid (cya) levels.

 

[pjt]

All pools are salt pools (to varying degrees).

My previous pool in California had a salt level of 5,000 after a few years of liquid chlorine, muriatic acid, and a few tabs. I didn't have a SWG at the time, but if I still owned that house I'd install one.

Now he says we will have to switch to chlorine

You have a chlorine pool now, you're simply generating it yourself with your SWG instead of buying it at the store.

will install an inline chlorine dispenser

Not recommended.

I was looking at ozone generators to help with using less chlorine.

Both of these ideas are also not recommended.

Ozone Systems - Further Reading

www.troublefreepool.com

Always maintain FC in relation to your CYA. I endeavor to never go below the target FC.

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

opinions/insight/tips on a maintaining chlorine pool with an inline chlorine dispenser?

Not realistic for long-term chlorination of your pool. You already have an SWG, which is an excellent way to chlorinate.

 

[linck]

With the more experienced eyes viewing and posting on this thread, their responses are way better than the PB. This is your pool, I would not allow the PB to remove/replace the SWG with an inline tablet feeder. Long term use of tablets introduces small amounts of salt and increases cyanuric acid (cya) levels.

Thanks for your reply. I am hoping for a solution. I wonder what the solution to the eroding concrete under the cover will be? It was sealed and is not even a year old yet.

Why would they make this type of cover if it will cause potential problems with decking or is this just the wrong type decking for an automatic cover?

 

[linck]

All pools are salt pools (to varying degrees).

My previous pool in California had a salt level of 5,000 after a few years of liquid chlorine, muriatic acid, and a few tabs. I didn't have a SWG at the time, but if I still owned that house I'd install one.


You have a chlorine pool now, you're simply generating it yourself with your SWG instead of buying it at the store.


Not recommended.


Both of these ideas are also not recommended.

Ozone Systems - Further Reading

www.troublefreepool.com

Always maintain FC in relation to your CYA. I endeavor to never go below the target FC.

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

Not realistic for long-term chlorination of your pool. You already have an SWG, which is an excellent way to chlorinate.

Thanks for your detailed reply. I would like to keep the SWG. I would also like to figure out a permanent fix for the concrete. This is really disappointing to have happen.

 

[ajw22]

You know what sealer product was put on the concrete?

There are some sealers specifically to protect concrete from salt or whatever is causing it.

Salt on Concrete: How to Protect Your Driveway – PROSOCO

Salt damages concrete by causing corrosion under the surface, leading to discolored, and cracked concrete. Let's prevent or fix these issues:

prosoco.com

Good quality concrete is more resistant to salt damage. If further protected with an effective sealer like Saltguard, Saltguard WB, or Saltguard VOC you can easily prevent salt damage to concrete.

Effects of Salt on Concrete

The better quality the concrete and pacement, the less likely that salt’s effects will have an adverse effect.

www.chaneyenterprises.com

https://www.cement.org/docs/default-source/fc_concrete_technology/durability/is536-types-and-causes-of-concrete-deterioration.pdf?sfvrsn=4

 

[linck]

You know what sealer product was put on the concrete?

There are some sealers specifically to protect concrete from salt or whatever is causing it.

Salt on Concrete: How to Protect Your Driveway – PROSOCO

Salt damages concrete by causing corrosion under the surface, leading to discolored, and cracked concrete. Let's prevent or fix these issues:

prosoco.com

Good quality concrete is more resistant to salt damage. If further protected with an effective sealer like Saltguard, Saltguard WB, or Saltguard VOC you can easily prevent salt damage to concrete.

Effects of Salt on Concrete

The better quality the concrete and pacement, the less likely that salt’s effects will have an adverse effect.

www.chaneyenterprises.com

https://www.cement.org/docs/default-source/fc_concrete_technology/durability/is536-types-and-causes-of-concrete-deterioration.pdf?sfvrsn=4

The sealer was Surfkoat Luster Sheild. I was curious if it was the sealer or perhaps needed another coat, but wow, to only last 7-8 months. We were really consistent about keeping the deck rinsed with the hose but I suspect when the cover closes it dips down into the water dragging some of the water up on the concrete to sit there.

 

[Newdude]

The salt/concrete concerns stem from sidewalks and road that need de-icing in the winter. That salting equates to many times over sea water salinity. And yes. It causes damage.

Even with seawater it takes years and years for bridge supports and sea (retaining) walls to weather while getting pounded 24/7.

A 'salt pool' at 10% the salinity of sea water will not weather concrete anytime soon. Moisture on the other hand, will begin finding the quality flaws of any material right away.

 

[JoyfulNoise]

The causes of concrete pitting are many -

Why Did My New Concrete Driveway Peel & Flake? | Homesteady

A properly prepared and poured concrete driveway should not degrade for many years. If a relatively new driveway shows peeling and flaking, the concrete mixture was wrong, or the installation was not properly done.

homesteady.com

My guess is that water was retained under the cover in those areas and there was probably inadequate sealing. This allowed water to infiltrate into the sealer/concrete and then freeze/thaw cycling caused the pits. You have stamped and colored concrete there. Depending on what concrete mix was specified, how and when it was stamped and allowed to setup and cure, and when the top coat color and sealer was applied, then all of those steps could easily lead to defects.

It may be possible to recolor and seal those pits and then they would blend into the surrounding deck. Right now it’s exposed concrete (grey) against a darker background and so the contrast looks horrible.

 

[linck]

The salt/concrete concerns stem from sidewalks and road that need de-icing in the winter. That salting equates to many times over sea water salinity. And yes. It causes damage.

Even with seawater it takes years and years for bridge supports and sea (retaining) walls to weather while getting pounded 24/7.

A 'salt pool' at 10% the salinity of sea water will not weather concrete anytime soon. Moisture on the other hand, will begin finding the quality flaws of any material right away.

So you think this was not properly sealed, allowing water to get in causing the problem? I am looking for a cause and a solution. I would rather keep the SWG than switch to an inline chlorinator any day but I also do not want the deck to disintigrate or look awful every time we close the cover for an extended period. I don't even know at this point if that concrete can be removed if/when it gets worse and something else put in. Again, the pool was completed in June, so isnt even a year old yet.

 

[Newdude]

So you think this was not properly sealed, allowing water to get in causing the problem?

I would guess the mix wasn't whatever consistency would be more robust.

Sealing would be a possible short term solution to a long term problem. Maybe their sealer wasn't the best either. It's hard to say after the fact other than it not the pools fault.