Quote Originally Posted by Jakebear
Larry,

I use a FAS-DPD kit (Taylor K-1515A)---using a 25ml sample you will get a resolution on the end point within .2ppm --- That is 2/10ths

The results I posted were a mix of mine and pool store --- Some stores use a colorimeter which yields results to .1 but since I don't trust the stores techniques or calibrations (if they did any) --- you can probably round their numbers off to the nearest whole number.
IF they are using a LaMotte Waterlink colorimeter then they are not waiting for the TC result to stop moving on the meter. I have seen this happen where I work when inexperienced people do the test. The FC test needs to be read within 30 seconds and the TC needs to be read at 1 minute for accurate results!