I had already put 5 gallons in around 9:30 pm before I saw your last post. At 10:30 pm I read FC @ 17ppm and CC @ 4ppm. At 6:30 am I read FC @ 1ppm and CC @ 1ppm. This evening was FC @ 0 and CC @ 0.5ppm. I'm baffled! Thanks for your help. Marty