I just had two scheduled power outages last week while PG&E was installing new 'switches' in my neighborhood. Each outage was scheduled to last two hours so I wasn't too worried. As it turns out, each outage was only one hour so I didn't do anything except hook up my battery powered air pump. I had my generator tuned up and ready to go however, just in case the outages lasted longer....as they've been known to do when PG&E is involved. Of course, it helped that I knew the outages were coming since they sent out notices in the mail; I worry far more about the unscheduled outages that have been known to last for a day or more.
The battery powered air pumps are great...and cheap! They automatically turn on when the power goes out and will keep your water moving and airated. I think mine was made by Penn-Plax.
But, if your outages regularly last for days instead of hours, a generator is the way to go IMO. I picked up a Coleman Powermate 1850 at Home Depot for around $350. It's enough to run everything on the tank except the MH lights, plus it'll run my computer, satellite TV, refrigerator, lights etc. Of course, you don't have to buy a generator; you can rent them for about $35/day at most rental shops.