Our plaster pool was completed last fall, and water kept balanced, adding muriatic acid weekly to keep pH down until pool was closed for winter. Upon opening this Spring, the plaster below the winter water level now feels rough (like sandpaper) and appears to have a whiteish haze on the surface of the gray plaster. The plaster that was out of the water during the winter is still smooth (top step and several inches below tile line). We just noticed this last week when it warmed up enough to get into the pool for the first time.
I suspect this is scale due to rising pH over the winter? The pool builder closed the pool in the fall, and this being our first pool, we assumed he would do whatever was necessary with the chemicals prior to closing. When he opened the pool, I noticed that he had to add about 3/4 gallon of muriatic acid, so I know the pH was very high by Springtime. The water was very clear within 24 hours of opening.
My water is balanced now, but what can I do about restoring the smooth surface to the plaster?
My current readings are:
CYA = 40
TA = 100
ph = 7.8 (I keep adding muriatic acid to bring it back to 7.4)
chlorine approx 5 (I have a SWG)
CH = between 200 and 250 (not sure how to read test to know exactly when color changes from red to lavender to blue)
The water is sparkling clear
CSI is currently within the proper range to prevent scaling, but how do I get rid of the roughness that happened over the winter. And then how do I prevent it from happening again next winter?