Hi,

You mentioned you have a heater - if this is the case, you do need calcium in your water. Your liner doesn't need it, but your heater does. The range is 200 to 400ppm I believe. I have been keeping mine at about 170 and I'm in line with the Langelier Saturation Index so I'm not increasing to 200 or above. Here's the link: http://www.advancedh2o.com/technical.../langlier.html

The others on the forum are much more knowlegable about the other numbers so I will leave that to them.

Hope this helps!
Tracy