In another post somewhere, I've read that when testing higher levels of chlorine, where 0.5 ppm accuracy isn't needed, that you could use 5 ml of tap water and 5 ml of pool water, and each drop should be equal to 1 ppm instead of 0.5. However, in practice, it doesn't work that way at all. When I test it (using well water, no CL in it), it doesn't turn very pink and 3 or 4 drops clears it up. However, actual CL level is 7.5, so it seems that it's actually multiply the drops times 2.
My CYA is high, and need to replace most of the water, but will wait to do that till spring. I know CL is high, and I don't really want/need 0.5 ppm accuracy, and was looking to save some reagent. What am I doing wrong?