Every day, when I brush, I see small clouds come off the wall, leaving the stains behind. Even though FC is at 33, and Ph at 7.2 it keeps coming back. The stains are kinda scaly looking, and I suspect they will not ever go away.
Also I'm uncertain about testing with the K-2006 kit:
The disappearing black spot is sort of imprecise. When I perceive it to be gone, tube is below the 100 line, so I'm guessing about 110. When I test with strips I get 50-100.
Also for the alkalinity test it says count drops til it turns from green to red, but it only gets to a yellow tint, and after that no change when additional drops are added, if I just base reading on when the green fades to yellow, alkalinity is around 90. Are Taylor's instructions for color change a bit inexact?
Any insights will be appreciated. I just started taking after the pool when the chemical service I've used for 25 years lost control of the algae.