Chlorine test disparity

[Altarocks]

I use a TF-100 test kit. I'm getting different Cl test results from the chlorine drop test and the included K-1000 vial test. I use the K-1000 color test daily and have performed the drop test twice now - the drop test results have shown FC far higher than the K-1000 readings.

2 days ago my K-1000 showed Total Chlorine midway between the 3 & 5 color standards. Just for kicks I performed the drop test - took 14 drops for the solution to turn back clear, = 7ppm. CC was zero giving TC = 7.

This morning my K-1000 showed a slightly darker gold/yellow than the highest standard of 5. I ran another drop test and this time it took 24 drops = 12 ppm. CC was again 0, giving TC = 12. Ran a 2nd K-1000 test to verify - this one showed similar color to the first one.

As an additional test, I used a Poolmaster kit my wife bought last summer. While it may be unreliable, the test color appears between 2-3.

Notes:

1. my pH is low because I'm in the process of lowering my TA. TA was at 400 when I filled 5 days ago and it's now down to 260 (well water). Running a homemade bubbler.
2. CYA seems to be creeping up, but it may be due to subjectivity in test results or use of trichlor. I recorded a reading of 35 a couple days ago and today recorded 50.
3. I have slowly increased the FC levels over 5 days. Was at 4 three days ago. Added bleach a couple times and use chlorine pucks (which I removed this morning).

The TFP Chlorine/CYA chart for non-SWG shows Target FC of 4-6 for CYA of 30, 5-7 for CYA of 40, and 6-8 for CYA of 50. Since the K-1000 only gives TC results to 5 what is the best way to perform daily tests??

I have no chlorine smell, and the water doesn't burn skin or eyes. Surely the drop test results are wrong. Any idea why this would happen? I use the SpeedStir. My reagents are from last summer, but have been stored in a cool, dark place and aren't yet a year old.

 

[mknauss]

The K1000 lets you know whether you FC or not. Not accurately. Rely on the FAS-DPD (powder and drop test) for accuracy. There are youtube videos available to help. See PoolSchool.

If you have no chlorine smell that is good! Means you have nothing being actively neutralized by the chlorine. I run my FC at 10% of CYA and the water is perfect.

Burning of the eyes is from an improperly managed pH.

Take care ---

 

[pooldv]

Right, chlorine doesn't smell in a pool, CC is what people smell when they think they smell chlorine in a pool. More FC eliminates CC, not less. It is counterintuitive to what we think we've learned about pools. But, I can put my nose right to the water when my CYA is at 80 and my FC is at 12 ppm and I can't smell a thing except sweet water. And I can open my eyes underwater and not feel any discomfort at all.