Thanks Dave. The pool is in direct sun with no shade. That's about what I was thinking re the Dichlor to add the CYA. Would Trichlor add about as much CYA as Dichlor? I never had a good grasp of the difference between the two.

What about the calcium? Isn't that something I want to get in there right away to prevent corrosion of pipes and leeching from the walls? Or is that something that's not a big emergency, and I can chlorinate with Cal-hypo and Dichlor-Trichlor for a while to bring the CH/CYA levels up?