How long before it's an emergency?

[allycat]

We recently suffered a brief power outage due to wind (about 4-5 hours). We knew roughly when the power would be back, so I decided to just let the fishes chill instead of evacuating them, and they were fine.

When the power goes out, how long do we aquarists have before the dissolved oxygen crashes and ammonia spikes?

My tanks' params remained steady as per my 50% (or 2x25%) weekly water changes and results of API test kit (NO3/4 &ammonia), so that helped my stress some, but...

Guess I should just get some tests for dissolved oxygen, too. I know this depends largely on the stocking/circulation, but I'd just like to have estimates for average tanks.

[Pufferpunk]

I just had this happen. Power wound up being off for 11 hours. My 1st reef dish died after 3 1/2 hours but I think he might have been old. We spent the entire night up, using a hand pump & a pitcher, pouring tank water back into the tank over & over & over... for 8 hours straight. The most affected was the reef rank & my other SW tank & I kept going back to my fahaka's tank too, because he looked sad. There are the largest fish I have in that tank. All my FW tanks are planted pretty heavily, so I'm pretty sure they were better for it.

[RTR]

Part of the question depends on the filter format. You can easily pour through an HOB, but you have to dump a canister into shallow trays. For the tank itself, it depend on the bioload. High O2-demand tanks (like reefs) are at high risk, while understocked tanks are much safer.

[hadla]

makes me want to buy a small generator or battery operated thing to plug the filters into in case that ever happens

[allycat]

Ya, my GSP had the "sadness" you mentioned in your fahaka, PP. I kept checking him with a flashlight but it made him beg me to stay with him and I wanted him to stay calm.

One of my DP's fell asleep vertically stuck against part of the intake tube of her filter while it was off. I think this was her way of rebelling! They all kept inspecting the usual places where current was. Wish we could tell them it isn't our fault...

[Troender]

The problem depends on what kind of filter you have. The bacteria in external filters die off much quicker than in internal filter. I've actually (twice) forgot to replug an internal filter for almost 24 hours after a water change. Believe it or not, it went very well. Once it was even in a quarantine discus tank! But I didn't get any problems at all, all though I monitored the situation closely when I realized that the filter had been off for so long. In external filters it's not that easy. The bacteria will die off much more quickly. I haven't "tested" a very long time of no power on those, and I hope I never will. But I would expect problems.