I'm getting ready to do my first water change soon (1st fill was Thanksgiving)
Yesterday, I was in the tub (2006 HS Envoy) and noticed that there is a whitish, chalky like substance at the waterline of the tub all the way around. It's not obvious because of the light color of the tub (Sterling Marble). I can remove it with my fingernail and will use a nylon scrub to clean it off when I change the water.
But, What Is It?
My water chemistry has been excellent. Typically, pH 7.5, Alk 80, Calcuim 160 using a Taylor kit. I use dichlor for both maintenance and shock with (very) occasional use of MPS, Ozone and Silver Ion cartridges (Nature2). Vermonter dosing method. Have been shocking about every 2 weeks, but only if needed. Water quality has been great during this first cycle and I am changing the water because it's coming up on 4 months and CYA has now moved over 100.