First TF-100 Test - how are we looking?

Charlie G

New member
Dec 30, 2017
Houston, Texas
Up until now, we have been getting the in-store BioGuard "ALEX" test. The past few weeks, we've been told our chlorine is "high" but the pool also hasn't been getting much use due to travel and other summer activities. Currently, using TriChlor tabs in an in-line chlorinator

Just got our TF-100 and ran the first test this AM. Pump had been running about an hour or so by then. Pool looks pretty decent.

The drops indicated CL > 5.0 and a pH between 7.5-7.8. The digital pH meter showed 7.1, calibrated right before, so not really sure which to trust here (see pic below).

Remainder of the test was as follows:
FC - 8.5
CC - 0.0
TC - 8.5
CH - 300
TA - 100
CYA - >100 (black dot was gone about 2/3 of the way to the 100 line)
BOR - 15
Temp - 88.5°F
pH - see above

Any guidance would be appreciated. TIA



Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Welcome to the forum!
100 is the limit of the CYA test, so you have to do a diluted test. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. Multiply the result by 2 for your CYA level.
It is likely you will need to do a fairly large water drain/exchange. You should discontinue use of trichlor and use liquid chlorine.
I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.
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Gold Supporter
LifeTime Supporter
Jul 16, 2010
Portland, Oregon
My pH meter has been right on since I got it (with the TF-100). I have multiple other ways to measure pH, and so far it's right on.

I have a large comparator block that I use with R-0004 that I can compare the meter to. (more colors than the OTO to compare to).

I feel like with the major difference between the drops and the meter in your case points to a calibration issue. The drop test is always the most accurate.
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