Someone on the original thread posted last March asked about emergency power when they live in an apartment and can't have a generator. There are several solutions, but the first one is to assess whether you truly can't have a genny. If you've an outside deck/balcony, you may be able to get away with a small, quiet generator like the Honda EU2000i. They're highly portable, incredibly reliable, and small enough to be stored in a closet.
If you live in an apartment that doesn't have a deck or balcony, then a generator isn't possible. In this instance, you've several options, from the least preferable to the best:
1) Battery powered air pump running on "D" cells. Buy lots of D cells, and unless you've a tiny nano, several air pumps.
2) Computer UPS. These are readily available, but the problem is that they're designed for a relatively short power interruption - typically 20 minutes of run time for a computer to allow you to safely shut it down. If you're only powering a small powerhead, they'll last longer, but the battery power you have at your disposal is still far, far less than solution #4, below.
3) Integrated backup power systems for one of your power heads, ala the Vortech battery backups or the Tunze "safety switch" devices. The advantage to the Vortech solution is that it is constantly charged when not in use, so you really don't have to think about it. The downside is that this only handles flow.
4) One or more marine batteries and an inverter. Typical inverters will supply about 1500 watts of power, though they can of course be purchased with considerably greater capacity. During an outage, a 100W heater, a 50w return pump and 50watts of powerheads will last about 5 - 10 hours when powered with a standard 85 amp-hour marine battery and an inverter, depending on how much the heater runs. Shedding the heater and the powerheads and just running the return pump gets you about 20 hours. Typically, you'd want 2 marine batteries per tank for 20g - 100g tank sizes, one that's running the tank, and one that you're charging at a friend's/relative's that has power. Besides the batteries and inverter, you'll also need a charger, of course.
5) Even better, a charger/inverter that you can purchase from a place like The Inverter Store, and several 85 amp-hour or larger marine batteries. The advantage to this sort of setup is that you plug the charger/inverter into the wall, your reef into the charger/inverter, and the batteries into the charger/inverter. This gives you instant-on backup in a power outage, charges the batteries (and maintains them that way) when the power returns, and operates 24/7 whether you're there or not.
