Preparing for a Power Outage in Winter


Apr 21, 2009
Preparing for a Power Outage in Winter

by Frank Greco, staff
Copyright 1997 by Frank M. Greco. Used with permission.

When winter is upon you, it's a good idea to make plans for maintaining your aquarium during a power outage. Even a short outage can lead to disaster and loss of animals if you are not prepared.

The first thing to do in an outage is to unplug your filters. If the power is off for a long time, toxins such as hydrogen sulphide and ammonia build up in the filter. When the power comes back on, the filter will spew this toxic cocktail back into your tank, perhaps killing the fish. Once power is restored, clean out all filters before using them.

Preserving biological filtration is another matter. If you use rotating biowheels, remove them from the unit and submerge them in the tank proper. For fluidized bed filters, remove as much water as possible from the unit, leaving the sand covered by only 1/4" to 1/2". For trickle filters, you can pour water through them once an hour or so or wrap them in plastic film in order to maintain humidity. Of course, for any of these filters, hooking them up to a 12-volt bait pump (small bilge pumps) will ensure their continued operation. During a power failure in cold weather, maintain temperature as best you can. Since glass is a poor insulator, heat loss can be rapid as the house temperature drops. Perhaps the easiest way to prevent heat loss is to wrap the tank in Styrofoam or some type of insulating blanket (the thermal type, such as are used to insulate water heaters).

Styrofoam can be purchased in sheets and cut to fit the size of the tank. Make sure it is a tight fit, and use duct tape to fasten the pieces together. Do not forget to insulate the bottom of the tank (if it is exposed) and the top. Punch a few small holes in the top for the airlines.

If you are using an insulating blanket, wrap it around the tank, using duct tape to keep it in place. While these methods will not prevent heat loss, they will slow it down. Never heat tank water on the stove and pour it back into the tank. Such wide temperature swings will virtually ensure that your fish will come down with a parasitic infestation. Better to allow the temperature to slowly drop, since the fish will adjust to it (to a point), than to play temperature see-saw.

Next, work on aeration and filtration. The simplest way to aerate is to remove buckets (or cups, if it's a small tank) of tank water and pouring them back into the tank from a height of 6 inches. Do this at least once an hour, more if the animals seem to need it. Another simple method involves hooking an airstone to a bicycle pump and pumping air into the tank as above.

The addition of 1 cc of 3% hydrogen peroxide per 10 gallons once an hour can also be used, but this is good only for short power outages since the addition of too much peroxide will destroy the biological filter. This should be used only as a last resort.

Perhaps the best way to aerate/filter your tank is to use battery-powered air pumps. There are two types available to the hobbyist, one of which works on "D" batteries while the other works on a 12-volt car or boat battery. Either will work, but the life of the "D" cell pump is short and you will have to replace batteries often. The 12-volt pump is better.

Hook your air pump to an airstone or boxfilter containing carbon and zeolite, or, better yet, a biologically active sponge filter and box filter combo. A 12-volt bait pump (bilge pump) may also be used to aerate/filter the tank, but they use more power than most 12-volt air pumps. The air lines should be run through the cover.

Unless you know the power will be off for a long time, do not feed the fish. Most fish can survive 3-5 days without feeding. If you must feed (for the health of the animal or your own piece of mind), feed sparingly. Remember, your tank's life support system has been compromised, and adding more organics will hasten water degradation.

If you follow my advice, your aquatic charges should make it through the power outage with little or no problems. Once the outage is over, do a 25% water change (remember to use your gravel cleaning siphon) and replace the carbon or whatever chemical filtrants you are using. Also watch for signs of disease (mostly Ich, which looks like white spots) and treat as necessary.


Author: Frank M. Greco
Title: Preparing for a power outage in winter Summary: What to do about filtration and aeration, and how to insulate tanks.
Contact for editing purposes:
Date first published: 2000
Reprinted from Aquarticles:
Nov. 2002, Fish Talk, Atlanta Area Aquarium Association.
June 2003: Translated into Hebrew language, by Kfir Alfandary of the Israeli Fish Forum in Tel Aviv, at:
July 2003: The Aqua Times, Lorain County Aquarium Soc.
September 2003: The Fishmonger, Vancouver Aquatic Hobbyist Club ARTICLE USE:
Internet publication (club or non-profit web site):
1. Credit author, original publication, and Aquarticles.
2. Link to and original website if applicable.
3. Advise Aquarticles
Printed publication:
Mail one printed copy to each of:
Frank M. Greco,
c/o The New York Aquarium,
Boardwalk & West 8th Street,
N.Y. 11224
#205 - 5525 West Boulevard
Vancouver, British Columbia
V6M 3W6


Apr 25, 2009
Brisbane Australia
THis happens alot in summer here in Brisbane Aus. WE have alot of storms and you need a back up the worst is when you are away from your tanks and you don't know or if you are away on holidays I have a box with everything in there and new bateries and an step by step info sheet for the person I call to help if there is a reason I can't get to the fish room. lealea


Global Moderators
Staff member
Apr 22, 2009
Burrum Heads, Queensland, Australia
I thought for a longer power outage I would add in my article as its helped save many a fish at my place.

First of all, my fish tanks are all connected to a 100w electric airpump as standard. You could just use airstones and sponge filters but I have gone for the undergravel filters as the gravel can hold and keep a lot of good bacteria for the tank. I have 29 fish tanks which on average are all 4ft so its quite a subtantial fishroom.

I have run that dripper garden tubing around the ceiling and I run airlines off it to each tank. If I find I need another airline for a frysaver or something, I just poke a hole in the tube and connect in a new airline. Too easy. :)

So what happens when the power goes off? Well like fun I am rotating umpteen battery air pumps to all those tanks so the best idea I found is to just keep running the 100watt electric airpump using an alternate power source.

When the power goes off, I simply have a power inverter and car battery. Turn the inverter on and plug in the airpump. It will run for a very long time. I have never run it till its flat and 100w pump on a 1000w inverter is not exactly taxing on the battery.

You can get inverters from shops like batteryworld or supercheap auto, etc.
Here's a link to an online one where you can download their catalogue and have a bit of a read up on whats available.

The best battery to use are the deep cycle batteries especially designed to be recharged many times, like boat or caravan batteries. They call them deep cycle, but you can at at pinch just use a normal car battery.

Here is a smaller inverter, my hubby Les just set up for my fishroom airpump (100w runs 29 fish tanks). I really don't need the big inverter and monster truck battery he also has and its heavy to be carting downstairs for use.

This one is just a 1000w inverter, with two power points and cost $300. We just have an old car battery that we had spare here and it was doing nothing so we thought we might as well put it to use.
The box is just a chook nesting box from Petcity for $11 as Les said he couldn't make one for as cheap as that.
He has even put castors on the bottom so I can wheel it out of the way when I don't need it, and chest handles on the side to make it easy to carry.



Retired Staff
Apr 8, 2009
Thanks Brenda, I think the fact that you have written the above warrants a bit more credit than being tagged on to an article copied from aqua-articles, so ill make yours into its own:yes: