Testing CYA question


Well-known member
Jul 23, 2020
In the TF-100 kit, the directions are to fill the supplied bottle with the reagent up to the label and the rest with pool water. Further reading leads me to believe this is a 50/50 mix or, about 15 ml of each (reagent and pool water)

My question is whether or not I can make a smaller batch. With a SWG and the corresponding high CYA, I don’t fill the tube too high to get my reading (70). As long as I mix up a 50/50 batch, is there any reason I won’t get an accurate result with a smaller batch?


Gold Supporter
TFP Guide
Nov 12, 2017
Central California
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
Rancho Cucamonga, CA
I did just that the last time I tested. I know the Taylor comparator uses a small sample size. I mixed 10 ml/10 ml and had a large enough for CYA sample for as low as 50 ppm (IIRC). Since the reagent has a long shelf life, why not conserve. Fill the CYA tube with 20 ml and see how low it gets you.
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Well-known member
Jul 23, 2020
I don't know. But the CYA R-0013 reagent is cheap! So why fool around with the test instructions? For $15 you can test 'till your ❤'s content!

Actually, I’m getting low and I don’t want to have to buy more until next year. I’m about to close the pool for the season.
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