The dpd./fas test in Ben's kit will test accurately up to 50 ppm. Alternatively, if you have one of the OTO kits that measures up to 3, you can dilute one part pool water with one part distilled water, and test from a thoroughly mixed sample, then multiply your results by 2. If still too yellow, then dilute 1:2 and multiply by 3. It's a ballpark, because you lose a little accuracy with each dilution, but it'll be enough to get you started.

What level of chlorine is safe for your pool depends on your CYA level, and you really need to have an accurate number to determine correct chlorine levels to kill the algae. If you stick with the best guess table, it'll be okay for your liner.

Janet