Does CYA Reagent Go Bad? (Low Chlorine Consumption with low CYA Reading)


Active member
Apr 26, 2017
Waterford, MI
Is there any chance this stuff loses potency and could give falsely low readings? I did buy a Taylor 2006 kit, but am saving that until I start running my equipment next week (doing tile repair on Monday, topping off the water level and turning on the equipment Tues-Wed), so I've been testing ph/cya/chlorine using a store-bought test kit from last year that I keep in a kitchen drawer. I've run the cya test three times (once in my kitchen, twice outside on sunny days), and all three times came up with a reading lower than 30 (i.e. fill tube to top, can still see dot clearly, although grayish rather than black). But my chlorine burn doesn't seem high enough. From my understanding of reading the threads here, minimal CYA should lead to very rapid chlorine consumption. Over the 24 hour period ending yesterday evening, I lost about 3 FC (from ~6 to ~3 per drop test). It was a sunny day in the mid 60s. Pool water is the right color and transparent, though there is a fair amount of dirt/etc. I need to vacuum off the bottom once I start up the equipment.

Should I be expecting a higher burn rate if the CYA reading was accurate? Or is it likely I have more CYA than the test is telling me? Or am I fine, and can go ahead and up the CYA once I get the jets on (or do I even need to)?

edit (add): The reason I'm concerned is that I don't want to add in extra CYA if I'm actually higher than the test says, and end up over-doing it.


TFP Expert
LifeTime Supporter
Jul 21, 2011
Eastern Ohio
For starters, WELCOME!

As per your question, yes CYA reagent does go bad. That said, it'll go bad agter several years of storing it incorrectly. Your reagent is fine I'm sure after only a year.

As per your FC loss,
This time of the year it's very common to have low FC loss as the sun isn't out in full force just yet. With 30ppm CYA a loss of 3 isn't shocking at all. I'd let things go a few more days as you get the equipment dialed in then retest and see your results. You can add CYA slowly then.

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