I don't have a calcium hardness test in my little kit, it has been on the low side since the pool was new and I have slowly added calcium hardness. I have been doing it slowly because my local PS, tends to tell you to add to much according to the PB.
I have cleaned the filter lots of times since pool was new, this however is first time since the surface has cured I saw the milky dust from cleaning. I knew when the surface was brand new it was normal, now that the pool is not new, that is why I am worried. I am going to PS for complete H2O test tonight after work and will post results.

I had a second filter so I installed that to get pressure down and will acid wash and dishwashing detergent the old one to clear it up .