Wanted to share this.
We got a new pool a month ago. This is an inground pool 26000 gal.
The pool got white and grey spots. Pool builder wanted to drain the pool and do a acid wash. I read online and found acid wash shaves few years off the plaster, so I told him let's do No Drain Acid Wash. He had never done this before, but I thought no harm anyways as afterwards we will do acid wash if does not work.
Anyways. We added about 15 Gallons of muriatic acid in pool and turned off all the pumps, skimmers etc. Let it sit overnight and started brushing next day. Within 2 days the color of the pool started to look much better and mottling spots and grey spots were gone. This is only after 48 hours and brushing 4-5 times a day with steel brush. All pumps and skimmer were off during these 48 hours.
I immediately at this point (after 48 hours) decided to rebalance. The TA was almost 0 and very very low Chlorine. PH was way below 6. So we added the 20lb Alkalinity Up (from Leslie pools). Stirred it in pool as much as I could and turned on skimmer pump at full speed. After 4 hours I then added 15 pounds of Soda Ash with pump running full speed. The result was
Ph - 7.2
Phosphates - None
The pool looks beautiful. Please note- I did not brush at areas too much where discoloration was not a problem. I did not wanted to etch the plaster too much and acted quickly on rebalancing in 48 hours.
The only issue is now water is cloudy. But I have researched and they say turn on all your water features and pumps and aerated the water. So we will see. I will update soon on cloudiness.