Losing? How? Since Watermom told me several days ago to keep adding chlorine, I have kept my chlorine level in the orange color range of the OTO chart that she sent me. I'm checking it twice a day. The lowest it's gotten is dark yellow. That has been over a week now. During that time my PH has stayed at 7.2 and my TA near 110 until tonight when they were 7.5 and 150. Is it possible that the algae is dead, but so intertwined with the scale that removing it requires a lot of brushing? The algae is no longer green, rather kind of an ochre/light brown color.
My HTH kit came with the same instructions you linked, so I have been following the correct procedure. The good news is when I tried it again tonight, it worked and I was able to get a hardness reading of 310. I wonder if the kit has a "floor" it won't give results below.
Another little bit of good news is I saved a good piece of change when a lawn tractor repair I needed to do cost me almost nothing other than my labor and some good luck. I immediately ordered a K2006. I'll have it Thursday. I'll keep testing with the HTH until then, but I'll share my new test results Thursday night.