My pool has been open a few days. The pool company usually dumps in some chlorine and once I get all of the gunk cleared it typically clears and I take over testing and balancing. This year it is still green so I was planning to start SLAMing today. I use the TF-100 test kit. My CYA test doesn't seem to be working. The black dot isn't disappearing, leading me to believe it is less than 20. I've used the same test/chemicals last season and it worked fine. Could it be that the chemicals have gone bad? I'm not sure how much chlorine to add without knowing the true CYA level. Thoughts?