I ran a test with my CYA level of 55 against the Chemgeek Chlorine / CYA chart and the results didn't return what I expected.
Poolcalc
CYA 55
Normal 3-6
Shock 15
Mustard Algae Shock 24
(the previous non-beta calc gave 4,9,17,32 as the corresponding values)
Chemgeek CYA chart (approximate...