Crystals shedding out of KrystalKrete

[Sean_C]

So, we had an 8500 gallon saltwater pool installed last year. The installation process started in April of 2021 and the KrystalKrete finish was applied and filled with water on Oct 27, 2021. The pool then sat, because the pump was not wired, until Nov 4, 2021. The contractor was in charge of the startup and balancing for the next 4 weeks (ended up not being quite 4) and turned it over to us. Long story shorter, we ended up with scale by January of 2022. They came out and drained, acid washed, and refilled (on our dime) mid February of 2022. Since then we've been noticing what appeared to be sand in the bottom of the pool when the walls and floors are brushed. Come to find out, it's the crystals or marcite (I believe the pool store called it) shedding from the interior. We have been fighting the pH since the pool was finished. It gets to 8 every week and I or the pool service company have to add muriatic acid to bring it down.
My questions are:
1) Will the interior have to be chiseled and reshot?
2) We had a service company but in their contract they stipulate they're not responsible for interiors, so who is responsible? We have a One year warranty on the interior from the builder.

I'll attach pics along with a printout of our last 2 water sample results. We no longer have the pool servicing company. I'll be doing it myself from this point and just taking samples to Pinch a Penny for testing.
I couldn't attach everything I wanted for some reason.

 

[SoDel]

Can you post test results?

 

[Sean_C]

Here's the results from the other day...

 

[SoDel]

If I’m reading your numbers right, your saturation index is way too low (what they report as Langlier index). Did anyone add anything lately to get the pH that low? Do you have a service managing your water or are you doing this yourself? At those levels, the odds of precipitating calcium are extremely low (or like zero) and etching the plaster is much more likely. Something else is going on. I’d call the builder for a diagnosis and action plan before the year guarantee runs out.

In the mean time I’d aerate the water to get the pH back up. If you are using a pool service, you need to have a discussion with them about getting the saturation index under control or fire them, buy a good test kit and do it yourself. Either CH or TA (or both depending on how you want to manage it) need to go up. It looks to me, depending on what your CYA levels are, that your actual carbonate alkalinity is extremely and unusually low.

edit: just noticed your CYA is reported and at 100 ppm — your carbonate alkalinity is too low. Did somebody recently add a lot of acid to this pool? You’ll also need to drain some water and replace to get that CYA down.

 

[ajw22]

Your variance between your two tests illustrates why we do not give advice based on pool store tests.

Get yourself the Taylor K-2006C or TF100 Test Kits , do your own tests, post the result, and we will be happy to assist you. Also get the K-1766 Taylor Salt Test since you have a SWG.

Pool Test Kits - Further Reading

www.troublefreepool.com

pH rising to 8 on new plaster in a week is normal for a year or more.

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