Quote Originally Posted by nefretrameses View Post
My local Leslie's still insists that FC/CYA ratios are crap. Here are my latest test results and treatment method
:
Here's my question. I use test strips (I know!) between tests with my Taylor kit to monitor FC. While the Taylor kit reads 10.0 the strips read 3. I know the Taylor test "unbinds" the chlorine attached to CYA which is then part of the result. I assume that test strips do NOT "unbind" chlorine attached to CYA and that (in addition to their inherent inaccuracy) is the reason for the different readings. Or am I off base?
No, the test strips are inaccurate because simply exposing a chemical to the water to indicate concentration is tricky since it relies on diffusion/circulation and approximate amounts of water pulled out and onto the test strip, among other factors. The drop-based kits rely on precise stoichiometry for chemical reactions.

The FC/CYA ratio is not crap. It's science and proven in tens of thousands of pools. Print out and give the Leslie's person this scientific peer-reviewed paper and if they still can't figure it out then print out and show them this post and if they still can't figure it out then print out and show them the "Chlorine/CYA Relationship" section of this post and if they still don't understand it, well, give up.