I believe the recommendation here is to use liquid chlorine rather than the pucks because the pucks contain other chemicals that affect other factors (CYA?). Whereas the liquid chlorine only affects the FC.
THIS!^^^^If you have added 8 lbs of stabilizer your pool has over 50 ppm CYA in it if 18000 gallons.
That adds 10 to the result on top of rounding up. Let's say the actual value is 32. The dot is visible at 30, gone at 40. Your method calls it 50. Just using the first number where the dot disappears is already rounding up to the next 10, and is consistent with the test instructions.Repeat until you do not see the dot with a GLANCE. Then use the next highest number for your CYA. If you stop at the 40 line, use 50.
The above is not possible. The lines come up from the bottom. So if you see the dot at 40, but not at 30, you use 40.The dot is visible at 30, gone at 40. Your method calls it 50.
The above is not possible. The lines come up from the bottom. So if you see the dot at 40, but not at 30, you use 40.