The drop kit I have from Walmart I'm not sure I trust to measure CC. You have to measure FC by dropping 5 drops of OTO, then reading within 10 seconds to get FC. Then, after 2 minutes it "fully develops" and you can read TC. Each time I've tested, the water has never "developed" more after the initial 10 second wait, so either I have no CC (which is odd; we've been using the pool and the dog gets in there constantly) or the test is bad. I'm waiting on my PS234, which I hope has a better way to measure CC.

I'm still interested in knowing whether bleach dissipates at a constant speed, given all other variables are the same. That is, will a full jug of Cl be gone in twice the time as half a jug? Or is there a level of Cl which, when reached, will tend to stay in the pool longer?