Spa staining/mottling not seen in pool

[Lonnybass]

Good morning,

I am hoping to get some guidance on some staining or mottling that is ONLY in my hot tub, and not seen in my pool. I have tried using the Jack's Magic test kit and results were inconclusive. Since taking over the pool I have gotten my water levels balanced, so I wonder if what I am seeing is the result of previously unaddressed calcium scaling or something else. The pool plaster looks relatively pristine and spotless in comparison, so I'm not quite sure what might be going on. Would love some guidance so I can do some treatment work during the offseason here in San Diego. Thanks!

 

[ajw22]

Post a complete set of test results including CSI.

Mottling is what plaster often does. Not much you can do about it. Be happy it is in a small area. Any treatment like an acid wash would be more damaging to your finish then is warranted.

 

[Lonnybass]

Test results

FC 5
CC 0
pH 7.4
TA 80
CYA 40
CH 200

We just completed a reverse osmosis and my water has since been rebalanced - unfortunately I did not grab a CSI reading beforehand to see what it had been like before taking over the pool.