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How to Save your Aquarium in case of a Power Outage

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Power outage aquarium fish tank can easily turn your years of hard work, pleasures, and hassles you went through into complete waste. I hope you are not here because you have not power your self right now, but in case you do, this article will tell you what to do! There are several crucial aspects you have to focus on if the power outage exceeds one hour.


Filtration system is the most critical concern for your fish tank during a power outage. It can kill the bacteria colony that have built up in your tank. They help with the nitrogen cycle to help convert the ammonia that your fish produce. If the colony dies, the ammonia concentration will increase and ultimately kill your fish and other aquatic life. You have to make sure that there is new water present for your bacteria that basically feeds them.

If you have a hang-on-back filter have the most risk. When there is no water flowing the beneficial bacteria that are housed in your filter do not have access to constant water. To solve this, detach the biowheels and then submerge these in the tank. You can put the filter media in the trickle filters in a mesh and put it inside the tank. You can also pour some water over the media regularly every hour. 

For other filters, the best thing you can do is put them in a mesh to put in your tank, as it is difficult to refresh water in your canister filter. Make sure to disconnect the canister filter and other filters because they can turn anaerobe fast and can produce toxic substances that can mean the death of your fish. Among these substances is hydrogen sulfite with a smell similar to rotten eggs. Another substance is ammonia. You have to clean every filter before you restart them if you are sure the colony has passed. The problem then is that you have no bacteria running the nitrogen cycle, so you have to get your hands on already cycled filter medium and do regular water changes in order to try and safe your fish.


Being cold blooded animals, you have to provide fish with the ideal water temperature for them, either through a chiller or a heater. Most of the times your tank’s temperature will drop because you normally rely on a heater to maintain the aquarium’s temperature.

Glass is not a good insulator, and this means that your tank will quickly adapt to the temperature in the room once your heater fails because of a power outage. This is the first point where you can slow down the effect the power outage will have on your tank. To maintain temperature stability, Styrofoam or blankets come in handy. You can wrap your tank with Styrofoam or blankets to slow down temperature loss. Do this first! Because of the added insulation the temperature will change slower.

If you are living in an environment that is warm, in the summer for example, you might rely on a chiller to keep your aquarium water from becoming too warm. In this case you can add ice to the aquarium. The best case is frozen bottles, so you better have them prepared! If not, you can often buy ice in grocery stores. Add this to a bag and put it in the water. The reason for both the bottle and the bag is because you preferably do not want the water from the ice mixing with your aquarium water.

The moment the power comes back, see to it that you adjust the temperature little by little to normal since extreme changes may result to extreme stress on your fish.


Levels of oxygen in your tank will decrease once the water temperature increases. Oxygen enters water through gas exchange that takes place at the surface of the water. Blowing some air into that plastic tube connected to the air pump will have very limited effects. The air stone will provide little to no oxygen at all.

To boost levels of oxygen, you have to take out some water using a cup and then pour this back in the aquarium. You have to repeat this at least once every hour or the moment you see your fish gasping for air. Lower temperatures in the tank will not just hold more amounts of oxygen, it will also slow down the metabolism of fish.

Other considerations

During power outage aquarium fish tank, avoid feeding your fish because they can actually survive 3 to 5 days even without food. Feed them sparingly if you really have to. Once the power resumes, replace the carbon, siphon the gravel, and perform a 20% water change. You also have to watch out for any disease. Most bacteria and parasites are already present in the water and they can attack weak fish any time. Power outage aquarium fish tank can be very stressful and there is a high chance for these diseases to kick in.


To conclude, make sure you keep the bacteria in your filter alive by providing new tank water to simulate a flow. If not your bacteria will die and you risk an ammonia spike that will kill your fish.
Secondly, the temperature of the aquarium water will quickly adapt to the surrounding temperature because glass is a very poor insulator. If you want to keep your aquarium from cooling you have to insulate the aquarium with foam and blankets. If you want to keep your aquarium water cool as the temperature is raising you have to add frozen bottles of water to keep the water cool.
The oxygen level in the water will drop because warm water can hold less oxygen than cooler water. Another reason might be that you normally rely on an air stone or filter to cause surface agitation and enable gas exchanges. To keep the oxygen level on point you have to scoop some water in a glass and pour it back in, to cause surface agitation.

Good luck, and I hope all goes well.


Cover picture by Crystal and licensed under CC2.0 no changes made

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