Thanks for the help. Yes, I did clean the filter about a week after I added, so I may have washed some of it away (still in the habit from the baquacil). Did a retest this morning, waist high outside in the daylight and it is still testing low. Water temp is in the 80's (I'm in Nashville are too DavidD). I will take a sample to the pool store just to double check myself. I probably washed a lot of it away!