Removing scale stains below water line

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D

Damsroy

Active member
Dec 15, 2022
38
CT
Pool Size
21000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
I removed the mesh winter cover two weeks ago since water was where I want it to be. More rain was coming and decided to use the auto cover until opening.

When I removed the winter cover I didn't notice any scale stains. I don't think there was any. Two weeks later I opened the auto cover to test the water and start an early cleaning and noticed scaled build up’s going from the auto cover tracks to below the water line.

No pbs removing the stains above the water line. I used MA and it was quite easy.

How do you remove those same staines below the water line, on the tiles and on the quartz finish. Do I need to lower the water so I can rub with MA or is there a technique without lowering the water?
 

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It looks like your pH tends to run on the high side. Have you had a large fresh water replacement lately? It looks like last season your CH was at 400 and its currently showing 250. 400ppm for CH is not outrageous but it is on the high side. With persistently high ph that could cause scale formation when the calcium drops out of solution and deposits itself on your pool surfaces. You likely have some scale on the pool walls and floor as well. Try lowering the pH to 7.0 and keeping it there for a while and the scale will release from the pool surfaces and go back into solution.
 
Thank you. Lot of rain this winter. I probably had to pump out water three times over the course of the winter. And this is after lowering at closing all the way to the returns. Added MA a couple of times during the winter. 3 cups each time.

Tested PH yesterday and it was above 8. Very purple. I would guess 8.5. Added 4 cups of MA with a pump running in water to mix it in.
Now at 7.8/7.6.

You recommend that I lower it even further before I restart the pool? I plan to start the pool early April this year.
 
Yes. Keeping the pH on the low end of the acceptable range will help the calcium stay in solution in the pool water and not deposit on tiles, walls, and floor. As the calcium releases back into solution you should notice your CH test result rise a bit.
 
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Will try this for a week. Thank you @zea3.
Build up above water line went away immediately with MA and a rag, but of course below water line…..not as easy!
 
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So added 7 cups of high strength MA. PH is now at 7.0. Hope this will make the calcium dissolve back in pool. Will report progress.
 
I have tried using 25% MA / 75% water and a toothbrush to remove white scale build-up on my tiles (using 31.25% MA), above and below the water line. I find that it leaves a dull finish. Almost seems as if the scale goes into solution and some of it adheres to the tile. Leaves a chalky reside. Dulls the finish of the tile...It comes off after time, a very long time. Erosion? I have resorted to plan B: carefully removing the scale build-up using a single-edge razor. It is almost impossible to scratch the tile, the scale comes off nicely, falls into the water and I never see it again, till it builds up again in the same place. Most of the scale is around the overflow waterfall spillway from the elevated Jacuzzi into the pool. The razor won't remove the dull finish caused by the MA solution.
 
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