Chlorine Testing Question

[cofive]

When i test for chlorine with my Taylor kit, I add the five drops of R-0001 and the five drops of R-0002, invert to mix and compare the color on the test block. I notice that the color will enhance for grow more pink as time goes on. Does this seem normal? Or at what point should the comparison be done? I've been reading it immediately after inverting to mix. I figure i'd ask here before contacting Taylor.

[chem geek]

It sounds like you are using the DPD chlorine test, such as in the K-2005 or K-1001 or similar test kit. If the water is cold, then it takes a little longer for the reaction with the dye. The tests are designed to be done with water at room temperature so I suggest keeping your sample capped and waiting for the water to warm up (you can use your hands to speed that up) to room temp.

If the water is at room temp and the sample gets darker over 10's of seconds or more, then that could mean high levels of Combined Chlorine. If you have a test with the R-0003 reagent you add after measuring FC, then use it and see if the Total Chlorine (TC) is quite a bit higher than Free Chlorine (FC). CC will slowly start to register as FC if you wait long enough, but usually it's at least 30 seconds or 1 minute before such interference becomes significant. If your water is at room temp, you should be able to measure it between 5 and 15 seconds after you've mixed and get a decent result. If you wait more than 30 seconds or certainly 1 minute, then you could get CC interference.

A more precise test for FC and CC is called the FAS-DPD chlorine test which may be found in the Taylor K-2006 test kit for a good online price here or the TF100 test kit from tftestkits.com here with the latter kit having 36% more volume of reagents so is comparably priced "per test". If you already have a K-2005 so only need the FAS-DPD chlorine test, you can get that here. A description and demo of the FAS-DPD chlorine test is here.

Richard