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How To Save Your Aquarium During And After A Power Outage

by Brian Dunleavy
How To Save Your Aquarium During And After A Power Outage

If you take a look at your aquarium setup, you will see a lot of electrical wires. These wires are the life support for your aquarium, so, if you were to experience a power outage, you need to know what to do.

If you have experienced a bad storm, you are probably very familiar with a power outage. Often, these outages last longer than a few hours, which can quickly become an issue for your fish and corals. 

Now, your approach will depend on how much livestock you have inside your aquarium, the size of your tank, and the type of power outage. 

The good news is, we have a quick guide on what to do if you experience a power outage! 

Types Of Power Outages

Depending on what type of power outage you are experiencing, will determine what approach you need to take. 

There are two types of power outages:

#1 Localized: 

This is when the main power source that is connected to your aquarium becomes disrupted, failed, or the plug has disconnected from the wall. 

This type of power outage is a simple fix! 

Simply plug the cables back into the sockets and check the circuit breaker. Usually, it is as easy as flicking the trip switch back on. 

#2 Generalized:

Generalized power outages happen when power lines have come down or the power is off due to a bad storm. These typically last a few hours or even days, depending on storm damage. 

When this happens, it is essential to unplug anything that could surge when the electricity comes back on. Most importantly, try not to panic, as you can save your aquarium!

Problems With Aquariums That Experience A Power Outage 

When the power goes out in your home, fish will shortly be starved of oxygen (O2). Reduced O2 levels can cause spikes in ammonia, and the more fish you have, the faster the ammonia will increase. 

To increase the O2 levels inside your aquarium, use a battery-powered air pump with an air stone to temporarily stabilize the O2 levels until the power comes back on. 

Another issue is temperature

When the power goes out, it can be challenging to control the temperature of the aquarium water. A sudden change in temperature increases stress, which can be fatal to your fish. 

As all your heating equipment requires electricity, it soon becomes useless when a power outage happens. Depending on the room temperature, will determine what you need to do.

For example, if the room is cold, then you need to retain heat, but if the room is warm, or you live in a humid environment, you will need to cool the water down. 

To Retain Heat:

  • If you have an aquarium lid, keep it closed. 

  • Cover your aquarium with blankets and towels.

  • If you have a gas or wood-burner fireplace, use this to your advantage.

Note: Smaller tanks will lose heat faster than larger ones!

To Decrease The Water Temperature:

  • Open any aquarium lids or covers. 

  • Float a few ice packs on the surface, in a plastic bag. Replace the ice packs until the temperature is stable. 


A Step-By-Step Guide To A Power Outage

Once you have the oxygen levels and temperature under control, now you can execute the power outage!

  1. Firstly, you want to get that filter up and running again. Empty the filter and give it a rinse to eliminate bad bacteria from being pumped back into the water when the power comes back on. 
  2. Prime the filter and return the media to it. 
  3. Plug the filter back in. 
  4. Depending on how long the power is out, you will want to perform a 50% water change, testing the temperature, ammonia, pH, nitrite, and nitrate levels in the process. 
  5. We recommend waiting 24 hours before you feed your fish again, and once you do, feed them small amounts if your water parameters are still unstable. 
  6. Next, monitor your fish’s behavior. Look out for signs of distress or illness. Unfortunately, white spot disease (Ich) is a common issue after a power outage, so make sure you have medication to hand, as long as its not a reef tank.  

How To Prepare For A Power Outage?

After you have experienced a power outage, we recommend preparing yourself for another one, as they are unpredictable. 

The best option is to buy an emergency generator to power your house should another power outage happen. A generator will not only prevent issues in your aquarium, but it means you won’t have to scramble around looking for candles or a torch!

Sadly, generators are not cheap, but we highly recommend investing in one if you have multiple aquarium setups. 

If you are not quite ready to invest in a generator, do not worry, as there are other options available. 

The next best thing would be battery-powered equipment to control the oxygen and temperature levels, and your aquarium’s filtration. Remember to keep some spare batteries at home to keep the equipment running. 

Using quality pumps like Ecotech Marine Votechs or Vectras are also great because they can be powered for up to 72 hours (depending on the model) with their dedicated battery back up.

Another option is an uninterrupted power supply (UPS). These are fantastic, as they kick in when the power goes out. You can connect all essential equipment like your aquarium heaters, lighting, and filters to the UPS. If you are frequently out of the house, we recommend a UPS, as they will automatically turn on if a power outage happens when you are not home. 



Power outages can happen at any time, so you need to be ready to tackle the issue head-on. If a power outage does happen, try not to panic, but you do need to act fast as they can be problematic for your fish and corals. 

If you have any questions regarding maintenance help, reefing supplies, or your next coral, contact the Reefco Team or drop by on weekends. 

by Brian Dunleavy