K-1000 but with bigger Chlorine scale

Donldson

TFP Expert
LifeTime Supporter
Jun 12, 2009
4,507
NW Ohio
The scale on the OTO test isn't useful for actual numbers. You're looking for a general "kind of in the neighborhood" sanity check between FAS-DPD testings, anything else is asking a lot for an OTO test.

Even if it was more reliable, it seems a lot easier to fix the CYA problem than to try to get special equipment to run it. The pH test loses reliability when the FC is over 10 as well, so that's not going to be as accurate as it should be.