I find that if I dry the Anova after use with a hand towel the amount of build-up is severly minimized. So, just take out of the water, let cool slightly, and then carefully disassemble (three pieces…the heater and propeller main until, the metal sleeve, and the plastic bottom piece) and dry as much as possible with a towel. Takes only a minute or two.
Also, I found a clean Anove heats the water quite a bit faster than one with a lot of build-up.