FC test


LifeTime Supporter
Apr 29, 2013
I have a quick question regarding my FC test with the TF 100 test kit. I watched the video recently on how to do the FC test with the TF 100 test kit and it says to fill to 10 mm line. I have been filling to the 25 mm and doing the test accordingly when I do my FC tests. It seems it might be a little more precise to fill to the 25mm line but I could be wrong. What is the consensus regarding this? By the way I have been using the TFP method since the middle of Sept. and appreciate all the info this site has provided along with answers given in the forums. Our pool looks great. Thanks again


Mod Squad
LifeTime Supporter
TFP Expert
May 19, 2010
Tucson, AZ
With 25ml, each drop is 0.2ppm while with 10ml, each drop is 0.5ppm. There is no need to be more precise than 0.5ppm, so save your reagent.