Quote Originally Posted by Zaphod
Waterbear,

My pool has a vinyl liner, so I haven't been testing for calcium. How does a heater change the need for calcium? Is it a scaling issue? I have read items suggesting that calcium is needed for pool plumbing, but I didn't understand the rationale.

If that's the case, what should be my target calcium number in ppm?

The heat pump I've selected has a titanium heat exchanger (the unit is by Jandy).
Titanium is not prone to corrosion like copper is but scaling is a problem in either one. If your calcium is high and your TA is high then it can become a problem.
Does any of that change the equation or advice?
No, pH is the factor that seems to have the greatest effect on whether the water is corrosive or scaling but it is also influenced by the CH and TA and temp.
I appreciate your comments.


Zaphod
It is generally accepted that calcium is not an issue in vinyl or fiberglass pools unless you have grouted tilework or a heater. Then it is ususally treated similar to a plaster pool for water balance. I am not an expert on this. Perhaps someone else will chime in?