What they mean on the chlorine test is that you can either run the test on a 10ml or a 25ml water sample. After you put in the R-0870 powder, you then add the R-0871 drops one at a time and swirl after each drop. Count how many drops you have to add to turn it clear. If you used a 10ml water sample, then you mulitiply the number of drops x 0.5. With a 25ml water sample, multiply the number of drops x 0.2. This will be your FC reading.

On the next part of the test (finding CC) again, you count drops and if you used the 10ml sample, multiply the numbers of drops x 0.5 and for the 25ml sample, it would be number of drops x 0.2.

Hope this helps.