This is for chem_geek or anyone who wants to chime in.
Coming into an unusually warm Spring after an unusually cold and wet Winter in GA, I've had a lot of SWG customers come in saying, "Yeah, the pool is a swamp."
Well, their salt level is 1600 ppm and their CYA is indistinguishable from 0ppm using the Taylor test... So of course now that the temperatures have skyrocketed out of the blue their pool is green.
So I work out the shock level, dose our sodium dichlor product, give them instructions, and clear up the pool. But when they come back in, I'm not seeing anywhere NEAR a +9 ppm per +10 ppm chlorine increase.
The only reason to recommend the dichlor product, which is ironically more expensive than the cal-hypo product when considering available chlorine and the fact that we pay less for it, is the value inherent in the free CYA. But I've been in dozens of situations (avg of 43 customers per day in the last month) where I should have gotten a CYA increase of 50+ and instead I'm seeing an increase of 10-20 (difficult to tell with the test).
I've called Taylor to ensure that I'm doing the test correctly and I've swapped out reagents to make sure they're fresh. (By the way, you can buy a gallon of Taylor CYA reagent from Leslie's for $24.99).
What am I not accounting for here?