Hopefully this great forum can once again answer my question. I've been maintaining my pool as a first year owner all season using the TFPM. I've yet to have any issues and my water is perfectly balanced. I just did my second CYA test of the season just out of curiosity. I find the reading to be a bit hard to decipher but seems like my CYA has dropped from 80 at opening to almost 50. Is that possible with back washing every two weeks, adding some water here and there and normal rainfall? If not, it could be that I misread the test but it's so hard to see when that black dot is actually gone.