R-0871 Chemical/Bottle Self Life and Disappearing CYA


Aug 2, 2019
Peoria AZ
FC 4.5 (TF-100), 7.0 (Leslie’s), 5+(OTO)
TC 7.0 (Leslie’s)
Ph 7.6
Alk 100
CYA 30

Not a new member, but an infrequent poster who forgot his username. Been troublefree for 2 years since I started.

Based on the large variation in FC test results as shown above, I’m wondering if my R-0871 may have gone bad. It is stored inside but has an expiration date of 2/19. However, I would expect it to weaken and give me a false higher result, not a lower one as shown. I believe the higher value considering how much chlorine I put in last night. Any thoughts on the chemical issue? Is there any way the dropper bottle has gone bad in some way, like the drops are too large? Does the dropper bottle ever wear out?

The reason I’m so concerned about FC right now is that contrary to all logic as researched here, is the fact that my CYA dropped to zero last spring and this spring, replenished with liquid conditioner, and right now sits at 30 when it was almost 50 a month ago. How is this possible? The tech at Leslie’s says they see this with pools that have auto fill systems, but that still makes no sense based on what is said here about CYA because I’ve only lost water through evaporation, and not enough through spillage to justify the drop.

The CYA has been low all summer, so I will admit that I am running tabs more than usual to cut down on the amount of chlorine I’m going through. I know this is contrary to troublefree but It hasn’t spiked my CYA. Any thoughts on what the deal is with my CYA?