Little white spots on plaster.

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Y

Yarzy

Bronze Supporter
Jul 16, 2020
221
Chalfont, PA
Hi everyone. I have had my pool for 3 years and when I opened it this year, I noticed a few little white spots on the steps. I tried brushing them and it did not do anything. Normally I would not mind, but they are RIGHT on the top step. Any ideas how to get rid of them? Thanks!IMG_0336.jpeg
 
Your pool math logs seem to show inconsistent pool care. You apparently used cal hypo shock to fix an algae/cloudiness problem. That’s not the right strategy - to fix green algae caused by low FC you need to do the SLAM process and only use liquid chlorine. Cal hypo is known to cause cloudiness in water and the rapid pH rise can cause calcium scaling especially on plaster. Those spots could be calcium scaling. You can try to spot etch them or use a medium grit sanding sponge to see if that helps.

Please re-review TFPs pool care recommendations and adjust your testing and pool care regimen accordingly.
 
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To be honest, after shocking the pool and waiting a day, the pool is crystal clear like it was a few days ago. FC was 3.5 prior to adding the shock but I think due to my high CYA, I was getting a little chlorine lock and had to up the amount of FC to get the same effect. Pool still looks 100% perfect right now after a day with zero CC from the TFTtest kit. PH was a little high (8.0) but I got that under control pretty easy with acid. As I understood it, there no added CYA in the shock I used as that would have just caused more of an issue. As for the white spots, they showed up after I opened the pool this year and I just got around to posting the question. I was able to remove them today with a pumice stone.
 
The only way to know for sure if your pool is algae free is to do an overnight chlorine loss test. If you lose 1.0ppm FC or more overnight, you have algae. Water can look very clear even with minimal amounts of algae as it is mainly planktonic (free floating) in its early stages of growth. An OCLT is the only way to rule out biological activity.

If the spots came off with a pumice stone, then it was probably calcium scale. Keeping your CSI in the negative range (0 to -0.3) will keep calcium scale at bay.
 
"Chlorine lock" is a made up pool store term that is used when the pool store employees have no clue what other useless chemical "magic" to over-charge you for.
Basically, there is no such thing as "chlorine lock".
 
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