Different results with CYA refill?

[dancu]

Last year maintaining my pool was a nightmare, spent $1500 in one season on poolsupplies!!
Found this site over the winter, got Ben's kit,studied the info and cleaned up my pool with BBB! I love it!
Tested a lot to get a feel for my pool
After raising and keeping the CYA at 40 for several weeks I added reagent
from the refill bottle, now it reads 25 consistently.
Checked with my Wallmart kit it says 40
Is the difference in accuracy normal ?

[aylad]

CYA is the most subjective test of them all--differences in lighting, distance of tube from eyes, length of time the solution sat on the counter before you poured it in the vial, etc, can all affect the test. The best thing you can do is try to be consistent..i.e. use the same lighting, same distance, same time of day, to be as consistent as you can. It's entirely possible that your CYA did lower, due to splashout or dilution.......

Janet

[Poconos]

I've tried several methods of viewing the dot. All within about +-5. For consistancy you can use something like a fluorescent desk lamp reflected off a white paper or card and view the tube by reflected light off the card. That is, no significant light hitting the tube from the top and all the light coming up the tube from the bottom. Check this against daylight viewing and see what you get. It presents a viewing scenario that can be repeated.
Al