When I got my first TF-100 test kit last year the powder was a light gray. I always keep my kit stored inside but even so, I'm in FL and humidity is high. I also have a few packets of silica gel I keep in my test kit thinking it should help with humidity.
When I broke out the kit after the winter I noticed the powder had darkened, but I assumed it was still good. It seemed to be working fine and I never had a reading of more than .5 CCs. But last week (my bad) I let the FC drop to 2 and I got a touch of algae. Still, my CCs tested <1. I brushed and shocked the pool and the FC held overnight on the first night. Since then I have been waiting for the chlorine to drop back to maintenance level before turning the SWG back on. No one has been swimming because we're both sick so it has taken a while.
Anyway, today I broke out the new powder I just received and was surprised to see it is a white color. When I tested I had a reading of 1 CC, so I suspect the old powder I was using was not giving me a good reading of CCs.
When the powder turns dark does that mean it is bad?
What is the shelf life of the powder supposed to be?