I have a regular taylor chlorine test that measures up to 5ppm that I have been using for awhile. I received in the mail a new fas-dpd chlorine test kit. When I use the reg. one it may measure 3ppm of chlorine in my pool and the other will say I have 28ppm. The directions say to use 2 dipper fulls of dpd powder. I assume that means 2 of the round end fulls of powder. What do you think I am doing wrong? Which should I believe?