pH Ceiling - Henry's Law of solubility of gas - Richard Falk chart of values

[onBalance]

Draining and refilling with fresh water (that doesn't contain sulfates) sometimes dissolves a calcium sulfate scale.
Otherwise, it requires sanding the residue off.
If there is a high content of calcium and sulfate, it can precipitate out and form crystals (scale) on the surface.

 

[ferretbone]

Thanks I'll look into that.

 

[Adam_FL]

Thanks I'll look into that.

Jacks #2 treatment (sulfamic acid) followed by lots of dilution worked for me.