These are a must:
http://www.petsmart.com/global/produ...=1127257305618
They automatically turn on when they sense no power and can run for up to 5 days on just 2 batteries. I have 2 on the way, I figure they give you more than enough time to get home if the power goes out. A generator is pretty much a must if you plan on going for days without power. These airpumps will take care of small outages.