Thank you Pat & waterbear - a couple more questions:

Will adding CYA stop the "shock" action? I think I am ok now - no more algae on walls or bottom. I'd like to notch back down to normal operating Chl levels. I had probs with too much CYA last year - I am nervous about it this year, as the trichlor pucks are my daily dosing method. If I am not to fear the CYA, what is the min amt I should put in to the pool? None of the pool stores in my area have ever carried the Taylor reagents - any suggestions? I know I can order them from Ben but I am not sure how long it will take being the busy season. With the mini kit, does it matter whose reagents I use so long as they are fresh?

Waterbear, I appreciate the pH-bleaching-out explanation. I thought I recalled it being something to consider and I even added sodium thio to the pH test to see if that would change things. I believe I am ready to maintain the chl at normal levels. If that is the case and I add the CYA as above, once the CHL comes down should I then reassess the true pH situation?

Any ideas on why my mom the lab director's test had such different readings from mine - tests taken within an hour of each other?

And just as an aside, with my vinyl pool I don't ever need to worry about the calcium levels at all, right?