Howdy neighbor from Flower Mound,
When I shocked the pool I had 0 CYA and added 20 3" tablets of Tri-chlor and I measured the CYA to be 30 but Leslie's measured it at 70. This test is very subjective as to "starts to disappear" and I've just started using my Taylor K-2005, so I'm not real confident of the CYA reading. Also, the tester only goes to 5 FC and I really don't know how high it is. I will buy the FAS-DPD tester tommorrow. I'll get the correct reading of FC and retest my CYA, then shocking it @ whatever level will work.