Yeah, an OTO kit allows you get a quick and dirty but reliable measure of your chlorine level. On my to-do list is to publish an extended color match on OTO, up to 50 ppm.

I'm going to be tied up, and mostly away from the forum for the next few days. But numerous people have reported that borate levels > 60 ppm have reduced their pools 'twitchiness', with respect to algae. If you want to look at that, I'll help you next week. On a pool your size, the cost would be negligible.