Good review of the basics. Over the years I have been out of town for extended periods of up to 42 days utilizing nothing more than mechanical feeders without any significant problems. Many of my tanks exist SOLELY on Aquarclear Quick powerhead attachments using filter floss in it. It works great as a sole filter as well as a water polisher. The one thing to check before an extended leave is the impellor. Over time it builds up slime ("biofilm") and should be regularly cleaned. If not and a temporary power failure occurs, it may not be able to restart when the power returns.