FC Test with less chemicals

I use one rounded scoop of powder but have never tried the 5 ml of water. Have you done a back to back test with the 10ml of water and 5 ml to see if they "match"? I think the 10ml uses little enough regents I do not worry about it.

Kim:cat:
 
Keep in mind, any time you use less volume, the precision of the test is decreased.

From Pool School - FAS-DPD Chlorine Test
The precision of the measurement is plus or minus one drop when up to 10 drops of titrant are used, or plus or minus 10% of the final reading, when more than 10 drops of titrant are used.
Right, so to illustrate, if you are using the 10 ml sample your error rate will be +/- 0.5 ppm up to 5 FC, 1 ppm at 10 FC, and 2 ppm at 20 FC. If you are using the 5 ml sample then your margin of error is double that. So a reading of 13 means your FC is between 10.5 and 15.5 (rounded).
 
Right, so to illustrate, if you are using the 10 ml sample your error rate will be +/- 0.5 ppm up to 5 FC, 1 ppm at 10 FC, and 2 ppm at 20 FC. If you are using the 5 ml sample then your margin of error is double that. So a reading of 13 means your FC is between 10.5 and 15.5 (rounded).

Maybe I am getting huge errors and that is my issue... doesn't seem to accurate at that rate... hmmm.
 
Okay thanks for the input. I have been using 1 round scoop of powder and 10ML water sample, but I tried it with 5Ml and got the same results, so that is why I posted the question. Seeing that the margin of error increases I will stick with the 10ML water sample. Thank you for all the responses.
 
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