Is A Basic Poolcare Oto Test Kit Adequate?

[poolcare novice]

This Taylor kit has a 'total' chlorine/bromine cell, a pH cell and a bottle of OTO solution and R-0600 Phenol Red solution. We use a floating chlorine cartridge so I do not worry about the bromine. I also have the instruction sheet (only) for our old Poolmaster Pool & Spa 3-way test kit which says:"..."'Free Chlorine Residual' is tested by adding 5 drops R-0600, cap vial, invert several times to mix, read result within 2-3 seconds. 'Combined Chlorine' is tested the same way except result must be read in 1-2 minutes..." Are these 2 completely different tests with different color standards on each kit? If so, which is the best test kit to use? Thank you.

[chem geek]

What you describe with the R-0600 OTO reagent is a very approximate method for distinguishing between Free Chlorine and Total Chlorine. That method is no longer recommended since it was never very accurate and in fact the OTO test itself is not very accurate. It is a quick-and-dirty test to see if there is any chlorine at all in a pool and very approximately how much, mostly as Total Chlorine (i.e. Combined+Free).

The best test kit to use is the Taylor K-2006 or the equivalent TFTestkits TF-100 where the latter has more reagents you use more often (see Test Kits Compared).

Since you are using Trichlor tabs/pucks, you will be building up Cyanuric Acid (CYA) over time and that will make the chlorine less effective because the active chlorine level will drop unless you proportionally raise the Free Chlorine (FC) level to maintain a constant FC/CYA ratio. See the Pool School for more info.