I am new to testing my own water. Twice I've tested my CYA using the CYA view tube until the black dot disappears. Both times it never reaches the 100 mark, meaning it is well over 100 ppm? It is an above ground pool with a vinyl liner. I would really rather not change out 75% of my water, and getting the water level too low and I would have to worry about my liner. If I did my math right it would cost about $85 on my water bill for about 10,000 gallons. My pool volume is about 16,400. I dont think there is a R/O service in my area. I'll have my local pool store test it and see what level they say it is. Anything I am missing?