Calcium build-up on liner?

[E-Pryb]

Hello,

I was wondering some thoughts on what I have going on with my pool liner. This year I started noticing my liner looking faded below the water line. I thought at first it was faded but after closer inspection, it is a film(prettty stubborn) that I'm able to scrape off with my finger nail. Some attached photos, it's consistent across the whole pool. In the pictures, the water is lowered ahead of closing.

My pool is currently winterized but I took the pictures to my local pool store (hadn't been there in 3 years) and they thought it was calcium deposits and would need a stain remover product. My pool was installed in 2019 and been following this site since 2020 with my own test kit.

Maybe of note, my pool is salt water but my SWG failed at the beginning of the season and I used 12.5% sodium hypochlorite liquid chlorine to maintain my chlorine levels all year while the warranty process, service visits and availability of a new SWG took all summer through the end of season.

I was just wondering some thoughts of others here if I can do anything now to confirm what it is and be ready to address it once I'm able to open it. If any additional information can help, please let me know.

Thanks for the help,

 

[ajw22]

It is likely waterline scum/scale. Try a Magic Eraser in a small area and see if it cleans it without removing any of the liner color.

Magic Eraser on Pools - Further Reading

www.troublefreepool.com

 

[JoyfulNoise]

Mind sharing water test results? It’s pretty easy to figure out what’s going on if we calculate your CSI.

Also, calcium scale is pretty easy to test - scrape some off if you can and put a few drops of acid on it (you can even use white vinegar if you want). If it’s calcium scale it will fizz like a soda can opening. You could also apply acid directly to scale and see if the vinyl returns to normal.

 

[E-Pryb]

Thanks for the feedback! My last readings from before closing are below. My TA got as high as 200 during the summer and I started to work on getting it lower. I'll try to get out there this week and pull back my winter cover to try the recommendations above.

FC:4.5
TA: 150
pH: 7.8
CH: 220
CYA: 50
Salt: 3600

 

[JoyfulNoise]

FC:4.5
TA: 150
pH: 7.8
CH: 220
CYA: 50
Salt: 3600

At normal pool temperatures (70-80F) water with that much carbonate and calcium hardness will definitely be in the scaling potential area (positive CSI value above +0.3). Vinyl surfaces can get hazy from mineral scale.

During the swim season, try to keep your TA a lot lower (below 100ppm if possible) and you’ll avoid scaling issues altogether. It also will help to keep your SWG clear of mineral buildup as well.

 

[E-Pryb]

Thank you for the response! I am going to plan on hand cleaning the 6-8" below the normal water line for aesthetics before opening this spring. If I get my TA in line, will the rest of any scaling that would exist on the liner clear itself up naturally or do I need to do anything special? Do I need to target a certain CSI for a period of time?

Thanks for everything!

Eric