Wildly divergent test results

This is a 12,000 gallon AG pool maintained with BBB, sand filter. Left uncovered over winter. After vacuuming some minor debris off the bottom I tested the water using AquaCheck-7 and AquaCheck-4 strips, the hydropools reagent test kit, and two pool stores. All tests were done on the same day with water collected the same way. The strips and reagents were freshly purchased.

Results as follows:

AC-7 strip:
TH = 50
TC = 3
FC = 2
pH = 7.4
TA =40
CYA = < 30

AC-4 strip:
FC = 1
pH = 7.2
TA = 40
CYA = < 30

HydroPools reagent:
FC = > 3 (solution turned very yellow)
pH = 7.8
TA = 70

Leslie's (reagent):
TH = 50
TC = 2
FC = 2
pH = 7.2
TA = 60
CYA = 50
TDS = 350

American Pools (computer):
TH = 101
TC = 1.3
FC = 1.3
pH = 7.5
TA = 63
CYA = 25
TDS = 0

The water is sparkling clear but feels hard.

1. I'm concerned about the CYA readings. My tests say it's low, Leslie's says it's enough, Am. Pools says I should add.

2. The TA is low on all tests. I can fix that easily enough but I don't know how that'll affect the pH of the water which comes in at between 7.2 and 7.8 in my own tests and they're the ones I ultimately rely on because I test every day. The pool stores are quite a ways away from here; having them run frequent testing is not feasible.

3. FC is low according to the pool stores and my test strips but very high with my reagent test. I'm baffled by this one.

In fact, I'm overall somewhat confused by these readings and am hoping for your guidance, input, and suggestions.

It sure is nice to be back :)

Anna