I recently bought and started using a TK-2006 test kit, which helped me successfully SLAM my pool. Years past, I always used the Pentair Rainbow kit that came with our house, which as everyone probably knows, only has an OTO chlorine test.
My question: if the OTO tests for TC, why does it's highest reading only go to 1 or 1.5 PPM of chlorine? That seems really insufficient, considering the (super awesome) TFPC method wants FC to be at 3 or above. Or asked another way: why does the TFPC want the FC levels to remain so "high," compared to what the industry standard says?
This question is purely because I'm curious.