CYA drop?

[Baker18]

Hi All
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.

 

[mgmoore7]

Could be, with those variables and testing variations.

 

[borjis]

that sounds reasonable given your water capacity.

I have a bit less water and cya & ch levels are affected when I do multiple back washes or draining due to rain fall.

 

[duraleigh]

That is a pretty good size drop but within reasonableness. CYA seems to drop on it's own by about 5 ppm monthly and it sounds like you are backwashing too much so it all adds up.

You should backwash when you see a 25% rise in your filter pressure. Many TFP'rs go all summer with maybe one backwash. Use the gauge as the test.