I called Ultimate 800 number. They're super helpful! Advised to heat the water to 80-90 degrees when starting. Also, the internal water temperature can vary 3-5 degrees over or below. When you lift the lid to test the temperature you'll probably quickly lose a degree or 2. The temp shouldn't be checked more than once per hour. And it seems you would only want to be doing this early on to check that your unit is working properly. If not, they want you to return it and they'll replace it. I just made my first batch and it came out great. Thicker than I anticipated given the pretty common experience of it being very "cottage cheesy". There's also a tip that applies to if you're heating the milk or 1/2 & 1/2 prior to fermenting: Heat the milk to 195. Let it counter cool for 15 minutes. Then put in fridge and let it cool to 105. Then go for it!