You are right to question the accuracy of the test strips...around here we call them "guess strips" and don't rely on them at all, because they are neither accurate or precise. They are good for telling you if there IS chlorine or if there ISN'T chlorine (sometimes), but don't depend on them for regular maintenance testing.

Sounds like you're doing the CYA test correctly--you view the tube from the top, holding it at waist level, and put the solution (reagent mixed with pool water, shaken VERY well) in until you can't see the black dot. It doesn't surprise me that your test result is different from the pool store--and I would go with yours.

The test kit that we normally recommend is the K-2006, which can be found at the Amazon link in my sig (anything that is purchased through this link results in a small donation to PoolForum, too). If you already have a kit that uses drops to test for pH, TA, CH, and the reagent test for CYA, then you can just add the K-1515 at the same page, which is just the chlorine test that uses powder and a drop system, and is capable of measuring accurately up to 50 ppm, as well as measuring CC.

I'll let the chemists explain why the chlorine levels need to be higher with the CYA being higher, but the bottom line is that as your CYA rises, so must your baseline chlorine. And yes, you do need to test chlorine at least daily to make sure that you're maintaining the required level to keep the pool from going green on you. Remember that the pucks are adding stabilizer, so if you continue to use those, you'll need to test for CYA occasionally, too. Not everyday, but I would say at least weekly or so if you're using the pucks on a regular basis.

Janet