Gray Mottling Plaster Discoloration

[HouTex]

Islandswan, I have the same problem (I think) and my plaster installer offered to do a no-drain acid wash followed by a drain and re-fill for $500. I decided it wasn't worth it. My plaster, while not perfect, doesn't look bad in full sun. Only at low light levels do you really notice the mottling. I've learned to live with it and I hope the mottling is only a cosmetic issue. My pool is coming up on two years old and the plaster is showing no signs of wear other than the mottling.

 

[MissFit]

We had our pool plastered about five months ago. We have never been able to get the finish to stop rubbing off. Now I'm seeing these little gray pitting places on the steps. The contractor insists that our chlorine levels MUST be kept between 1 and 3 religiously, siting a couple of dates when the new chlorinator was out of control and too much chlorine was dumped in. Finish was coming off BEFORE that and has continued. He says they won't honor the guarantee because of those times. I have monitored the chems twice daily for three weeks, micro managing the balance. The pool service people say I've done an amazing job and that they've never heard of chlorine being the cause of this problem. The only way we can get clear water is to floc and vacuum to waste. The next time we brush we can't see the bottom anymore. Does chlorine destroy plaster----permanently?

 

[onBalance]

No, chlorine does not degrade the plaster surface. One can pour straight bleach on plaster and not cause damage. As long as you have been maintaining the water balance (pH, TA, CH) within reasonable standards, then water chemistry is not what is causing the "dusting" of the pool finish. It would be interesting to know what your pool water chemistry readings are now, including the tap water readings for a comparison. The contractor's response is not accurate, and he should know better.