A loss of electrical power can be a great source of inconvenience and trouble, and always seems to occur at the worst possible time. And yes, this can be a dangerous situation for your fish. Some power outages will only last for an hour or so. These sorts of electrical losses are not so serious as those that may follow a tropical storm or other such disaster. It is in these times when the power may be out for a period of days, or possibly weeks that you will be surely tested as a fish-keeper. But, with a few precautions, a bit of extra work and a couple hardware 'tricks' even this problem can be safely overcome. Don't give up on your fish!

When electrical power is shut off to an aquarium, there are two things that will inevitably occur to threaten the well being of your fish. One: The loss of electrically powered filtration. Filtration that provides all important water movement to impart life-giving oxygenation and provide an efficient means of removing biological wastes (Ammonia/Nitrite) produced by the fish within the aquarium. Two: There will no longer be a source of electrical heat to maintain the water at a steady, stable temperature.

Prevention should be the first thing to consider, to minimize the danger a power loss will pose to your fish. A good first step would be to limit the amount of fish stocked within the tank. An aquarium so stuffed with fish, that power filtration is at its very limit in keeping up with oxygenation and safely removing the Bio-Load from the water, will not support the fish within it for very long when the electrical power fails. Oxygen levels will quickly drop due to fish respiration and even worse, levels of toxic Ammonia and Nitrite will rise to dangerous gill burning/fish killing levels in the water of an over-stocked tank.

The next step should be the purchase of battery powered air pumps. Waiting to the last minute, when a storm is imminent or the power has already failed, is not a good time to purchase these pumps, (or the batteries that power them). A good, basic rule of thumb is to provide a minimum of a single air pump with air stone, for every two feet of tank length.

A good cleaning/water change conducted the day prior to an event where electrical power loss seems imminent, such as with the arrival of a Tropical Storm or other natural disaster is a very good idea. Doing this maintenance, combined with no feeding of your fish the day prior will help to insure a head start on good water quality in the hours, days or possibly weeks to come, with no electrical power.

Battery powered air stones will insure the water stays oxygenated inside an aquarium. This is good, but mere oxygenation of the water will only solve part of the problem occurring with a loss of power filtration. Overcoming the waste load produced by the occupants within the tank, is a definite priority as well. This is where a sponge filter, run off of an air stone will definitely be of great service. But, a problem faced by most fish-keepers today however, lies in the use of these sponge filters, as most modern aquariums just don't use this sort of (wonky looking?) filtration anymore. Or do they?

Here are some examples of serviceable sponge filters made from intake pre-filters installed on various types of power filtration. From left to right we have pre-filtered intakes from a Penguin 330, Aqua Clear 300 and a FilStar XP-3 Canister:

Each of these pre-filtered intakes is basically a plastic tube, with handy sponge filter attached at the bottom. Beneficial filtration bacteria will colonize these sponge pre-filters, aiding in overall filtration. Placing a bubbling air stone down inside will draw water through the plastic tube and foam pre-filter. Current and most importantly - all important Biological Filtration will occur! Here is an air stone with an Aqua Clear 300 pre-filtered intake:

Removal of waste produced by the fish will become a serious priority with loss of power. In the first 24 to 36 hours after a power loss, the fish should not be fed at all, and only very, very lightly after that. Daily cleanings of waste from the substrate, with small amounts of water changed out, will insure levels of toxic Ammonia and Nitrite produced in the water remain manageable by your improvised, battery powered, sponge filtration. If you are on a water well system or live in an area that routinely loses water pressure with loss of electricity, you should give serious consideration to providing a ready source of pre-treated/conditioned water for your fish. This can be easily accomplished by the use of a water-filled plastic trash can, situated nearby the aquarium.

When the power does go off, and it seems likely that it will be for a longer duration than a few hours, then you must rig the aquarium for operation without power filtration.

1) Remove the glass tops. Doing this will insure proper aeration of the water within the tank for the fish, and enable easier access to the interior of the tank for performance of frequent cleanings or adjustments to improvised filtration equipment.

2) Unplug all electrical equipment connected to the aquarium. Periodic fits and starts of the electrical power to the aquarium will merely insure the destruction of un-primed power filtration or dangerous variations in temperature within.

3) Rig up your improvised, battery powered sponge filters and get those things running! Placing the top of the plastic tubes no more than an inch or so from the surface of the water will decrease water pressure on the air stone and insure vigorous bubbling and water current through the sponge pre-filter. The colony of beneficial filtration bacteria may be low in numbers initially on these sponges, but will grow out at a fast rate. The sooner they are started, the better they will work and the faster the tank will be replenished with oxygen.

4) Open up all canister filters to expose the water and media inside, to at least a bit of air and oxygen. Carefully rinse out all the canister media in de-chlorinated water, then return to the open canister media container. This will prevent the die off of all the beneficial bacteria colonized on the canister media and will help to establish biological filtration much faster in the aquarium once the electrical power returns. Remove and carefully rinse in de-chlorinated water all sponge filters and filter screens from Hang-On-Back power filters and simply place inside the aquarium. Much of the beneficial bacteria established on these filters will survive by doing this as well.

5) The last part will be insuring the water temperature remains stable and does not go too high, or too low. If in summer, the windows of the house must be opened to permit a bit of a cooling breeze to insure the water within the tank does not become too warm. Prevent direct sunlight from entering and heating the house by closing shades or curtains. In winter, it gets tougher. A kerosene burning heater will keep the air temperature within the house to a warm level. Keeping this kerosene space heater burning may be all you have available to keep the water warm enough for your tropical fish to survive. In the interim, heating water on a gas burning stove will provide a source of heat for the aquarium, but be careful! Heating the water directly like this is extremely dangerous, as water may be heated too fast causing a wide variation in temperature within the aquarium and a LOT of killing stress on your fish. When power does return, be careful to heat up the aquarium very slowly. Heating things back up inside an aquarium too fast after very low temperatures have been experienced, will almost certainly kill your fish. A terrible thing to happen in the end, after you've worked so hard to save them!

A loss of power can be very troublesome and annoying to say the least. But, with preparation, ingenuity and a bit of extra work, this will not necessarily mean certain disaster for your fish. In the fall of 2003, during the aftermath of Hurricane Isabel, I experienced 11 continuous days of NO electrical power, and NO running water!. By performing these emergency techniques on eight aquariums, containing a total of over 70 fish - I didn't experience the loss of a single fish! Good Luck with it, don't despair and most important - don't give up on your fish! □