I've reviewed this page:
I have two questions.
Is it necessary to swirl the entire time if you know your chlorine level is high? For instance a SHOCK chlorine level of 30 requires 60 drops. When undergoing my FAS-DPD test in the morning (performing a OCLT) I will usually just dump 50 drops in the tube, swirl it, and than go one at a time. Am I really affecting the results this way? I can see the need to swirl the entire time if your chlorine is low and you can clear your solution in 4-6 drops easily.
Also, can somebody clarify this line under notes?
- 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.
If I'm putting 60 drops in, I could be off by up to 6 drops? If I'm reading this right, how can you do a OCLT w/ high level of chlorine if you have a 10% margin of error? 10% of 30ppm is 3ppm, which is 3 times the level of the 1ppm or less chlorine drop which signifies a successful OCLT.