CYA testing unclear

[benny27]

I have the TF100 test kit on year 2 with it (new chemicals this year)
For the most part I have been able to keep a nice clear pool but the CYA test I just am not confident about. Last year I just had the pool store check it a few times. They are not doing tests at this time so I am on my own.
My testing I should have less than 20 CYA chlorine does not seam to be burning off vary fast with the sun so I am afraid to add stabilizer and end up with to much.
When doing the test it says fill up slowly till you can not see the black dot. Any pointers that could help me out would be nice
Intex metal frame pool
just did this test
FC - 4.5
CC 0
pH - 7.5
TA - 80
CH - 50
CYA - <20?

 

[mknauss]

When you do the CYA test, try this next time.

Once you have your solution ready, back to the sun, etc. Fill the vial to a line, say 80, lower the vial to your waist level and glance for the dot, you see it, add solution to the 70 line, glance, see it, repeat until you no longer see it with a glance. Then use the CYA value one step above the line you read. So if you stopped at 50, use 60 ppm CYA.

The vial is in logarithmic scale. So it is not viable to interpolate between the lines. Just use the whole numbers, such as 50, 40, 30, ....