Hopefully this will help other newbies like me. I bought a new house with a pool in the back and had no idea what I was getting into. The owners ran through "Pool School" with me in about 30 minutes, shooting from the hip!
Within a week my pool was getting cloudy and turning green. I found this forum and the help provided turned it around in 4 days to a clear blue pool. I just like looking at it if that makes sense.
Before I found this site I stopped at the pool store, bought a kit that didn't test everything, and later had a water sample tested.
Now nearly 3 weeks later I reread the store report and see what I didn't at the time.
CYA was measured at 90
FC = 3ppm
I has no idea this ratio was way off but the report was all "good" with only phosphates high at 400. Once I got the Tf100 kit I was able see the CYA and Fc levels and with info on this site found I needed a lot more chlorine at that CYA level. But by the time I figured this out the pool was green!
I'm sure no expert by any means buy I do understand the chemistry now and the water shows it. I have kept the FC level within the range on the table listed here using the extra shock I bought. A little goes a long way now. I have the CYA down to 50-55 and FC about 7