Combined Chlorine Test Question - TF-100


Gold Supporter
Jul 5, 2019
Chicago Suburbs

Brand new pool and spa owner here.

I'm on Day-2 of balancing the water in my pool and spa (separate bodies of water... separate mechanicals). I just SLAMMED my spa to get a 1.5 CC level down to 0. During my fist test after adding the PoolMath recommended amount of chlorine I used the TF-100 to do a FC/CC test. After completing the FC portion of the test, I moved to the CC test... added the 5 drops of R-0003... the vial turned pinkish... I added 2 drops of R-0871 (one drop at at time) and the water turned clear... which tells me my CC has dropped to 1.0. Great!

I got distracted, came back to the test after about 2-3 minutes, and the vial was pink again... a faint pink... but it took 1 more drop of R-0871 to make it clear again.

I then waited another 2 minutes, and it turned a faint pink again... again, adding 1 more drop of R-0871 made it clear.

My question... do I just use the initial reading of when it initially became clear? Or, are these other two valid?