For printing, I don't worry about it. Whatever the ambient temperature is, that's my printing temperature. For film I got a big gray plastic dishpan like they use in restrarants. I fill this with water at whatever temp I want to process at. The chemistry goes in beakers that get quickly adjusted to temp in a pan of hot or cold water. Then they go in the dishpan. I also set the SS tank in the dishpan when I'm not agitating so the heat of my hand doesn't affect it. Any good dial or liquid thermometer should react within a few seconds to temperature changes- what are you using for a thermometer? I find the dishpan will hold temperature within about a degree for the ten to fifteen minutes it takes me to do a roll or two.(posted 8679 days ago)