My pool was re-plastered in early March. The pool builders took care of pool for first two weeks with daily brushing and chemical additions. After handing back over to me, I have brushed at least twice a week and kept chemicals balanced. Below is the latest test results
pH = 7.5 ( I add 2 cups acid daily to keep pH at 7.5 )
FC = 3.5
TA = 60
CH = 250
CyA = 30
I've noticed a light light brown-yellowish stain appearing on the walls. I have not noticed this on the floors. Most of the staining is in the shallow end of the pool.
I have checked water daily for FC and pH since handed back over to me and my chlorine levels have never been below 2.5 ppm. My pH will increase over the day but doesn't go above 7.8 before adding acid. I'll add baking soda on occasion as the TA starts to drift down. And I do use the BBB method.
I thought I was being a good pool owner by keeping water balanced and walls and floor brushed but I still have some type of staining. I tried to take pictures but camera would not pick up the stain. Any suggestions on what I can do to see what is causing the staining and how to fix.