Help! I really need to know why/how my cya level has dropped and why alk test does not turn red. Levels are as follows today: FC 29 CC 0 ph 7.2 alk ? turned orangish at 75 (same results when I used the 10ml instructions in the test kit) cya 35-40 CYA was 80-90 a week ago I tested twice last night and twice tonight and it was the same. Regarding the Taylor K-2006 test kit. Is the only differece in the R0871 and the R0871C just the size? These questions may seem silly to some but I will get the hang of this. On the bright side, have not seen any more "brownish/yellow dust". Makes us VERY happy pool owners. One last question. Since we had the problem with mustard algae do you recommend the polyquat be used or not? We are undecided on it.