I think Pooldoc needs to check in on this one, at this point. I'll ask him to.

In AZ, it is not uncommon to have wildly high CH readings, especially if you're using cal-hypo to chlorinate with. OTOH, if your test results for CYA indicate a level of approximately 195 ppm, and you can easily run a pool with that level, as long as you follow the best guess chart and make sure your chlorine never drops below the minimum.

Let me email Ben and ask him to check in on this thread...