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How Long Can A Fish Tank Go Without Power (Electricity)

How Long Can A Fish Tank Go Without Power (Electricity)

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Power cuts might not be as prevalent in some parts of the world as they are in others, but for an aquarium owner, even a short stint without electricity can spell doom.

As such, it is imperative to familiarize yourself with the do’s and dont’s of maintaining a fish tank during a power outage. And most importantly, appreciate that some blackouts can go for days on end.

From experience, it is a lot easier to keep fish alive during a short-term power outage as long you implement emergency measures to mitigate the effect of reduced oxygen level, ammonia spikes, and heat loss if keeping tropical fish.

But in a longlived blackout, such as those caused by the forces of nature, including (but not limited to) blizzards, hurricanes, tornados, and wildfires, you may want to have an emergency power outage plan for your aquarium.

So, how long can fish live without power, you ask?

Well, it depends…

if we are talking a short period without power, that is anywhere from 3 to 9 hours (assuming your tank is not overstocked), then your fish will survive with just a few interventions. Ideally, you would need to insulate your tank with blankets if it’s too cold, plus figure out a way to keep ammonia levels down.

Enough oxygen is also crucial, so consider keeping an emergency battery-powered air pump around your house for such occasions.

Fish in an optimally stocked tank can last for a period anywhere from 3 to 12 hours without power. Whereas, in an understocked aquarium, they can survive for up to a day or two. Even so, the same fish will start dying in 3 to 9 hours if the power goes out in an overstocked tank.

On the flip side, keeping fish in a big tank alive, especially during a blackout lasting hours or even days is challenging without emergency supplies.

For that reason, I’ve outlined, in more detail, every point made above to give you a full picture of the kind of interventions you need to take, in whichever blackout situation.

Please read on.

How to Keep Your Fish Alive Without Power

As I’ve mentioned, there are several levels of interventions that you might have to take during a power outage to save your fish.

All of which will depend on the duration of the power cut, and on whether you had prior knowledge the electricity will go out or not.

For long power cuts such as those caused by storms and hurricanes, you would need to get emergency power supplies for your fish tank, which we will look at a little later.

At the moment, let’s first delve a little deeper into how you should react to an unexpected blackout.

So, with short unexpected power outages, there are three main things that happen, and you should be concerned about.

  • First, the temperature slowly deeps to the ambient or room setting, which is a nightmare for tropical fish, especially in winter.
  • Second, the oxygen content in the aquarium begins to deplete due to the fish consuming it and without an air pump to replenish to stock.
  • And third, waste builds up in the tank, and without any biological filtration actively taking place, ammonia begins to spike.

How to Heat Your Fish Tank Without Power (Electricity)

One thing you don’t want in a tropical fish tank is the temperature going to low. As such, during a blackout, the first thing you need to do is insulate your tank to make sure only the least amount of heat is lost.

Of course, if you already have a generator, you do not have anything to worry about. Just plug it in to start running the most essential equipment such as filters, air pumps, and heaters.

You can hold off from turning on the lights, more so when the power cut occurs during the day.

A UPS battery back up will also come in handy if you have one.

Now, if you don’t have any of these solutions, use any of these hacks to keep your fish tank warm.

#1 &mdash Mix Calcium Chloride With Water in a Bottle

This idea might sound worse than it is, same as any chemistry lingo. But you’ll just be mixing a type of salt with aquarium water.

Calcium chloride is in fact commonly used in different types of food, and to melt ice in places where roads and sidewalks get icy on Christmas; annoying right😒!

So, it’s pretty much an everyday use chemical.

To start the process, fill a 500ml (1.05 pints) bottle about 70 to 80 percent with tank water, then add in about 100 grams (3.5 ounces) worth of calcium chloride and give it a good shake.

The mix will result in an exothermic reaction, which means that the combination of the two substances releases heat. The solution will heat-up to an average of about 130° F

Since the solution is in a water bottle, obviously it’s not going to leak, and the reaction does not result in any gas leak or expansion of the container.

So, do not worry about it blowing apart.

To heat your fish tank, take the bottle and place it in the water. Depending on the amount of air in the container, it may sink or float.

If you need it to remain floating near the surface, reduce the solution to bump up the percentage of air inside the bottle. Air is lighter than water making the bottle buoyant

For more warming in your aquarium, you can use more bottles filled with the solution and place them on different areas in the tank.

The number of bottles you put in your tank will mostly depend on how big your tank is, the ambient room temperature, and how fast the temperature is dropping.

Please note that the heat in the bottle is not infinite, it will slowly drop to the tank temperature, albeit taking anywhere between 70 and 90 minutes.

Just make sure you monitor the tank temperature, if it gets too warm take the bottle out, and if the heat is not enough, put another bottle in the tank.

#2 &mdash Tape Heat Packs on to Your Aquarium

Heat packs are mostly used in gloves and hand warmer, but in the fish keeping hobby, they are also used for shipping fish.

Fortunately, they are not expensive, and you can access them quite easily from your local hardware store, hence an ideal solution in times of emergency blackouts.

How you use heat packs is by taping them on bottom of your fish tank, but make sure it on the outside, because they are not safe for use inside an aquarium.

Once you take the heat pack from the packaging, shake it first and give it a couple of minutes to heat up before placing it on your tank. Depending on the brand you get, you can expect it to heat up to an average of 130° F.

Because painter tape is not going to leave any sticky residue on your glass or acrylic, I would recommend using it to stick the heat pack on your tank.

Sticking the pack near the bottom of your fish tank ensures the heat will be transferred on to the lower section and slowly rise through the water column.

Cover the heat pack entirely as well to reflect as much heat into the tank as opposed to out of it.

In comparison, the water bottles are better at warming a fish tank, but using a heat pack is also effective particularly for small and nano aquariums.

#3 &mdash Wrap Your Tank in a Thermal Blanket

Thermal blankets are designed for survival helping to keep about 90 percent of your body heat even in snowy or rainy weather.

This ability to retain warmth can be tapped in times of a power outage to keep your tank from losing the heat it had accumulated before the electricity went out.

It is also a brilliant way to make sure you get the most of your gas generator while using it to heat up your aquarium.

While using a thermal blanket to keep your fish tank warm, you only need to wrap it entirely. Just leave a small opening at the top as you still need air to come in.

How to Oxygenate Your Tank During a Power Outage

Same as keeping your tank warm, there also are a couple of tricks you can use to aerate your tank during a blackout.

_Spoiler alert, some of these methods are quite interesting, for lack of a better word of course_😃.

#1 &mdash Create Oxygen with Peroxide and a Potato

Welcome to chemistry lesson 2.0!

So, when hydrogen peroxide decomposes by the action of a catalyst, it eventually turns into water and air, meaning if your can channel that oxygen into your tank, you can keep your fish alive even without power.

Luckily, the catalyst needed to decompose peroxide is readily available in many organic things, including in a potato.

This solution is particularly useful for fish keepers who like a neat DIY trick every once in a while.

Now, how do you inject this oxygen into your tank?

  1. First you’ll need 3 percent peroxide, which you can get from your local pharmaceutical store for two dollars or so. Then you will need a potato, but make sure you remove the skin before you start using it.
  2. Cutting the potato is also recommended to increase the reaction surface area and speed up the decomposition of the peroxide. Ideally, use half a potato to break down a cup of peroxide.
  3. Get a 500ml bottle and drill a hole on the cap, then insert an air hose about one inch into the container and make sure you create a tight seal around it.
  4. Attach an air stone to the other end of the hose and put it in your aquariums.
  5. Put the potato pieces into the bottle and add half a cup of peroxide to begin the decomposition to get water and oxygen.
  6. Within a few minutes pressure will build up pushing oxygen out of the bottle and into your aquarium. This will continue for about 4 hours at the same rate, and it can take up to a whole day for the peroxide to fully decompose.
  7. You should not worry about the foam or peroxide from the bottle getting into the tank because the odds of that happening are quite slim. here is a how-to video.

#2 &mdash Get a Battery Powered Air Pump

I’m sure not everyone is DIY savvy, or you might be a little busy for a project of the nature above, in which case, I would recommend getting a battery-powered air pump.

They are pretty simple units that run on D batteries, which should last for several hours.

All you need to do is plug in airline connected to an airstone and put it in your aquarium and turn the pump on.

With the air pump running, you’ll get some circulation within the aquarium and even get some flow around your DIY heating units for proper heat distribution.

It also creates some surface agitation, which will aid in gas exchange. This way, CO2 will be gassed off and be replaced by oxygen.

A battery-powered wavemaker should also come in handy to push water around your fish tank and create better surface agitation.

Fish Tank Filter Stopped Working After Power Outage

Your filter is the last thing you want to stop working in an aquarium, but most importantly, you want your ammonia level to remain as low as possible.

But how do you achieve this considering your fishes will keep producing waste during a power cut, even when the beneficial bacteria in the filter gradually slow down and die.

Well, not to worry because there are a few tricks around it.

First, you’ll want to take all of the media from your filter (or at least as much as you can), put it in a mesh bag, and place it over your air stone.

Of course, you will have the air stones running via your battery-powered air pump.

What will happen is that the water will be drawn through the media get filtered or at least feeding the bacteria and converting all the ammonia in your tank into nitrite and then nitrate.

That said, during a power outage, the only thing you do not want to do is feed your fish as that increases the waste load in a tank that is already limited in biological filtration capacity.

How to Prepare Your Fish Tank For A Power Outage

Since not all power cuts are unprecedented, you might want to prepare for a blackout beforehand.

Usually, there are two levels of preparedness.

One, there is what you want to do long before an imminent power cut, for instance buying a generator and other things like that…

…and two, the things you want to do just before the power goes out such as changing your water and feeding your fish one last time.

Let’s look at the process, then conclude with what to do after power is restored.

How to Prepare Your Fish Tank For a Power Outage

Immediately power goes out, there is an invisible timer that starts to count down, and before long, your fish start dropping. But there are a couple of things you can do to mitigate the losses or even extend the time it takes before your fish die.

First, if you anticipate a power cut, for instance in time of a tropical storm or winter power-cut, it’s recommended that you feed your fish one last.

Feed them a while before the scheduled blackout to give your fish enough time to eat and your filter an ample duration to clean out any leftover food.

Also perform a 10 to 25 percent water change. This will ensure that there is the least amount of waste in your tank before the power goes out, and before your filters come to a grinding halt.

Please note that you must continue doing the water changes during the blackout period to reduce the bioload in your tank and keep ammonia from accumulating.

In case you already have emergency aquarium equipment, you might also want to prep each one of them, just to make sure they can sustain your fish tank once the lights go out.

Before you plug in your equipment into the emergency power supply, remember to remove any unused or non-essential items to keep the consumption low.

You might need your aquarium lights at night in which case you can light them, albeit dimly. But during the day in a well-lit room, I recommend having them off because like your heater, they are enormous power hogs.

Rememeber, I stated before that having emergency equipment for your fish tank is a long term preparedness strategy. Most of the supplies you can buy anytime you have a few bucks to spare, even without an imminent power outage.

For that reason, I’ve made a list of the crucial power outage gear you would need to have to get your emergency plan rolling?

#1 &mdash Generator

A back-up generator is arguably one of the of most effective alternative ways to power your aquarium equipment when electric power is not available.

Usually, the generators run on gasoline, so you must have access to that, which is pretty accessible in the general scheme of things anyway.

The only downside of using a generator is they can get quite loud, though I’ve seen some really well-priced units that are rated super quiet, which is something you might want consider.

Also, please note that generators produce residual carbon dioxide much like a car’s engine, you therefore cannot use it in an enclosed area.

The best way is to put it in an open area with enough air circulation, but also remember to protect from adverse weather, more so if you live in a hurricane state.

That said, having been born and raised in Africa, I have had my fair share of generator-powered situations, and my brand knowledge is well vast. So trust me when I say get a Honda, Husqvarna, or anything within that class. They are easier to operate and will last you more than a long minute.

#2 &mdash Uninterruptible Power Supply

A UPS power pack is another good alternative for running your essential aquarium equipment when you do not have electricity.

However, sometimes this is only an ‘in-the-mean-time’ solution to give you time to get your generator running or prepare your DIY solutions.

Most UPS kits will only support your equipment for a limited duration depending on how big your fish tank is and how many items you are running.

After that, you’ll need electricity to recharge it.

#3 &mdash Battery Powered Air Pump

One thing that your tank needs most is air; oxygen in and carbon dioxide out.

Usually, the needed aeration is supplied by your aquarium filter via water movement and air pump. Of course, both of these items need electric power to run.

That said, short-duration power outages might not cause too much harm in your tank, but if you live in regions where the light can go out for up to, or even more than, 5 hours, then a battery-powered pump is well recommended.

Battery powered air pumps are inexpensive and will save you a boatload of events during a power outage. At 20 dollars, they are probably even cheaper than the fish you have in your tank.

Usually, they come either as manual and automatic.

The manual ones run only on battery power and work when you switch them on after a power outage. Automatic alternative, apart from running on battery power, they also come with a code to plug into a socket when there is electric power.

Even so, either unit will produce some movement of water in your tank, creating a current and aerating your aquarium.

Intrestingly, battery-powered air pumps are not only useful during a power outage, but are also an ideal aeration option on long rides home from a fish store, or when moving to a different state or city.

#4 &mdash Power Inverter

A DC to AC power inverter takes a DC current, such as battery-power, and convert it to 120 Volts AC similar to what you get from your wall mounted electric socket.

They are most useful during a prolonged power outage when you to run more equipment more than just an emergency battery-powered air pump.

An inverter will help get a standard 3 prong outlet kind of power, meaning you can run items like heaters and aquarium lights which run on an AC current.

#4 &mdash Zeolite

Zeolite is an effective way of removing ammonia, and because it can work in a short time, it’s an ideal emergency solution for aquariums without filters as during a power outage.

You can scatter it in the tank as the rock is harmless and will provide a large area for nitrifying bacteria to develop. One gram will remove up to 1.5 milligrams of ammonia.

Moreover, apart from during a power outage, zeolite is useful anytime you have an ammonia spike in your fish tank.

Thats all for this post, happy fish keeping.

Remember to follow us on Facebook and Instagram (@aquariawise) for more insight and aquarium discussions.

Eddie Waithaka

Resident Content Creator and Marketer at AquariaWise who talks about aquariums and fish and aquascapes a lot.

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