Taylor CH test chemical shelf life and potency


Silver Supporter
Nov 23, 2017
Port Orange, FL
I recently had a CH testing abnormality that I'd like to share, maybe it will help some others.

My CH numbers had been rather stable and predictable, generally running between 200 and 300. It would slowly drop with time from dilution and I'd bump it back with an adjustment. I recently got a reading of perhaps 100, but the endpoint wan't very obvious and definite. The last test was about 6 weeks earlier and it had measured 225. I checked it multiple times with both sample sizes and got repeatable results. I have an old kit bought maybe 3 years ago and have been replacing the high-use chemicals. However, some of the lesser used chemicals such as R-0011L and R-0012 were probably original. I figured I'd continue to use them as long as readings continued to make sense. Well, after the sketchy CH readings I replaced the entire Taylor kit figuring it was overdue. The CH reading with the new chemicals was 275 so evidently the old chemicals have truly "expired". What was odd was how those particular chemicals didn't slowly degrade, it appears at least one of them became useless over just a 6 week period.

I was looking at the new chemicals. Some give an actual expiration date but many give a "best by" date. Is there information anywhere regarding how the various chemicals degrade, how the results may change with age and how long they could be used?


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
The newer reagent bottles should all have expiration dates on them now. Yours just were old enough that this was coming in? I believe they're said to have an 18 month lifespan.