Power Outages

The goldfish tank could techinally go months without power, it would just require daily water changes. The tropical tank would also be ok for a few days, as long as your house temp. stayed above 65. I would imagine that that temp. would shock the fish, you may have an outbreak of some illness, but hopefully most would survive. If either filter is off for a while, you would want to replace the filter cartrige, and empty the water from the filter, because ive heard that toxins can build up in them.(I believe)

You can try a battery back up like the ones they make for computers but I don't know if they are worth it. The longest outage I have experienced was about 14 hours (and I've been around a pretty long time) which isn't long enough to really cause a lot of harm unless you have Discus or a reef tank. Its a good idea to have some ich medication around to put in the tank as a preventative. After the power comes back let the temp come back up on its own, don't hurry it along by adding warm water. Also a fairly large (~50%) water change would probably be in order. Depending on how long the power was out you would want to rinse out your filter media in some old tank water, but do not replace it. The last thing you want to have happen in this situation is to put your tank through a mini cycle.

ive recommended taking a look at this article before, and i still think its a good article. gives good ideas as to how to keep the stress down on fish

http://www.plantgeek.net/article_viewer.php?id=8

'Preventative' medications are not a good idea. Treating what might happen can cause serious problems--anywhere from irritation to the gills and slime coat of the fish, to a complete wipe out of the bacterial populations in the tank. Very bad things. Treat when there is a problem--not before. For ich specifically, it's a parasite. If it wasn't in the tank before the power outage or any other stress event, it will not suddenly appear.

For power outages--best bet for the fish is to ensure that the tanks are lightly stocked. Over stocked tanks can go bad very quickly without a running filter, while lighter stocks do better (less waste production, less oxygen use). If you expect long term power outages, this is even more crucial. Tropical tanks can be helped by covering/wrapping them with a blanket to reduce temperature dips, reduce feeding to reduce waste production, and plan for daily small water change. Battery operated air pumps (commonly available in fishing departments for live bait) can help with gas exchange. If you have enough invested in an aquarium, purchasing a generator is your best bet. I have one, just in case, that will run the pumps and some lighting for my SW setups, and the filters only for the FW systems.