Read the "Best Guess" page on the chlorine / CYA relationship => http://pool9.net/cl-cya/

Then answer the following questions:

1. How are you testing? (If it's not a K2005/2006 . . . you don't really know what your CYA level is!)

2. What is your chlorine level? (if you didn't use a K2006, and your chlorine is > 5 ppm . . . you don't really know what your Cl is!)

3. Is your Cl level appropriate for your CYA level? (if you haven't tested with a K2006, you can't tell)

4. Order a K2006, so you can tell. => http://pool9.net/test/

5. Meanwhile, since you're worried about your liner, and since we (probably) don't know what your Cl or CYA levels are, get some polyquat locally and add a QUADRUPLE dose. Polyquat is a chlorine compatible algaecide, but isn't super effective against mustard algae. Neither are other algaecides, but you can 'overdose' with polyquat without causing problems. => http://pool9.net/polyquat/

Things you need know:

+ Test strips = 'guess-strips', even when computer read by dealers, ESPECIALLY with respect to CYA.

+ Liners are unpredictably sensitive to chlorine bleaching. Dark blue is the worst.

+ The ONLY non-chlorine / non-bleaching genuine sanitizer pool system is STILL Baquacil / Softswim, etc (PHMB) => http://pool9.net/phmb/
PHMB works well the first season, but is a pain after that, UNLESS you follow the guidelines in our info. It's expensive, compared to chlorine, no matter what you do.

+ Until you have accurate test results, we can't tell you what to do in YOUR pool.

Good luck!