Shortly after closing my pool for the winter I got a gallon sample of pool water so I could play with my testkit which I was to get soon. Didn't order right away and I just got my TF100 and was starting to play and the first thing I did was the OTO for FC. It read zero.
Where I am confused is that I had a cheap pentair OTO and I was over 3 (strong yellow) when I tested when I got the sample. I did not have any algae or apparent CC. The jug sat in the shade in my poolhouse probably averaging 50 degrees over the last 7 weeks.
If I missed this in PS or another thread please advise. I thought FC would only break down by sunlight, bather load, or CC. Any idea how the FC got consumed in my jug (I rinsed with just water pretty good a used apple juice jug)? Noticed the PH is lower than I left it as well. Reading around 7.3 (strong 7.2) was at 7.8 with my pentair PH test when I did the sample back on 11/1/08.