This is my first post, looks like a great forum. I have read some parts of the forum and was convinced to get a good test kit rather than going to the pool shop thus I have acquired my own personal test kit. So after doing doing the first run (result accuracy may be a little off till I get the hang of it) I measured
CH not detected (in the 2 stage test the first stage indicated no CH)
and using a cheap digital TDS meter 1500.
Before I added anything to lift the calcium hardness I wanted to establish why as what I have read focuses on impact on cement and plaster based materials.