I have a Taylor K-2006 test kit which uses DPD powder for the free chlorine test. There are 2 options for volume of water sample- 10 ml and 25 ml. Two dippers of powder are specified for the test in both cases. Would 1 dipper be sufficient for the 10 ml samle? Also, sometimes a small amount of the powder will not dissolve, even when shaken vigorously. Will this affect the test results?