A few more ideas. I bought a dozen 500ml bottles from the 'bay for keeping mixed solutions. I too re-use stop a few times - I just keep track of how many times and then throw. I use an aquarium thermometer. I keep a 5L water bottle nearly full in the darkroom sink, and adjust the temperature in this before I start, then use water from the container to mix up the dev. When you clip your films to load the reels, keep the clippings to test your fixer before a session.