So let me set up the background first. I have a LaMotte Spin Lab with 301 CL/BR disks ( I know how you all feel about this). The updated 301 disk regaents have been reformulated to be more accurate (according to the LaMotte chemist who helped me update the software to accept the new disks and my numbers for CH and Borate are quite different from the 300 disk series). I also have a Taylor k-2006 from two winters ago which I had used twice (pre TFPC education). It was kept closed in a climate controlled basement and I assumed the reagents expired so I didn't really again use it until yesterday. I recently purchased the TF-100 test kit to get a clean start on testing this season. I also went to Leslies Pool Supply for a test (first time for me, they use taylor reagents, taylor speed stir and the sales person seemed knowledgeable).
I had some issues with the CH tests and figured out that that I had a fading end point. After reading this and trying it all my CH testing became more consistent.
So I have 3 different test kits, a pool store test and have results from 9 tests in all. All results from the test kits and Leslies are very close. Within .5ppm for FC, .1 for pH, 10ppm for TA and 25ppm to 30ppm for CH. But the CYA is inconsistent and concerns me.
Test 1 Spin Lab x2
Test 2 K-2006 x2
CYA 45 (Halfway between 40-50ppm)
Test 3 Leslies x1
Test 4 TF-100 x2
Test 5 TF-100 R-0013 and K-2006 test bottle and CYA tube x2
CYA 45 (Halfway between 40-50pp)
I have read and re read instructions, watched videos, used consistent lighting, used one eye and used my belt buckle for consistent distance.
Any thoughts on this would be helpful. I plan to do another series of tests today as a sanity check. My R-0013 supply is taking a beating though.