Aquarium Battery Backup – This Guide Could Save You $$$!

How many times has the power gone out and you immediately begin to worry about your aquarium? Have you been the victim to a power outage while away on vacation and you have come home to a stinky, dead aquarium?

I have been lucky where I live as we very rarely get power outages, however, a recent house fire in our street forced the utility company to isolate the street and for 6 hours I had no power. This made me very, very nervous and after that, I got a backup system and this is the article about my research and findings.

Battery backup systems work by providing power to life support systems during a power loss to keep your aquarium livestock safe. Aquarium battery backup systems slow the onset of decreasing oxygen, rising ammonia, and water temperature changes when an aquarium loses electrical power.

Aquarium Battery Backup Systems are available in several different formats:

  • Uninterruptible Power Supplies (UPS)
  • Aquarium Specific Battery Backups
  • Battery Powered Air Pumps
  • DIY Battery Backup Systems

If you want more information about my backup power system, I have set up a two-part system:

  1. Battery Backup (Short-Term Power)
    IceCap Battery Backup from
  2. Generator Backup (Long-Term Power)
    Honda EU1000i 1000-Watt Inverter Generator from
My Trusty Steed!

This way the Battery takes over for the periods when I’m not home, then the generator is easily set up for longer periods of no power. It works awesome!

Read on to find out what may be the best Battery Backup system for you and why…

What Happens In Aquariums When The Power Fails?

When aquariums lose electrical power the water will begin to lose oxygen, its temperature will change based on its surrounding climate and ammonia will begin to rise. Left without attention livestock can begin to die within 1-2 hours in small aquariums and several hours on large aquariums.

Lets look at each of these problems abit more closely:

  1. Oxygen Consumption
  2. Ammonia Rise
  3. Temperature Drop or Rise

Oxygen Consumption

This has to be your first concern because it is usually the one that will cause the first deaths in an aquarium, especially if you are heavily stocked (High Bio-Load).

As all living cells need oxygen to live, the cells in your aquarium’s inhabitants will continue to require oxygen even when the power goes out. The water in the aquarium can only hold so much dissolved oxygen and if it is not resupplied the animals within it can rapidly consume all the oxygen from the water.

Another problem you may have is a current algae bloom. Algae is a plant that when it dies it can decay rapidly. This decay will cause the bacteria in your aquarium to multiply because there is an abundance of food. More bacteria = more oxygen being consumed. Yep, even bacteria need oxygen to survive.

Oxygen replenishment should be your Number One concern when the power goes out as it will kill your fish way before the temperature drops, Unless its -40°C outside!

Ammonia Rise

The next task you need to sort out will be the rise of ammonia. As your fish are still living, so is their metabolism, which means they still go to the bathroom.

Under normal circumstances, the Nitrosomonas Bacteria living in your sand, rocks etc will be responsible for consuming this ammonia and converting it into the less toxic Nitrite. As these bacteria begin to die because of the lack of oxygen, the ability of your aquarium to manage ammonia decreases. This then causes the ammonia to rise.

Saltwater fish and coral are very sensitive creatures and once the ammonia level begins to reach 0.2 ppm (Parts Per Million) it becomes toxic. At 0.5ppm it is fatal. How fast it gets there is predicated on your bioload and how rapidly your Nitrifying Bacteria begin to die.

At this point, you are on your way to a tank crash.

Ways to prevent Ammonia Rise:

  • Use an ammonia test kit to monitor your ammonia level
  • Have an Ammonia Alert Badge ( Link) on stand-by to put in your tank during power outages.
  • Small water changes every 6 hours. Be sure to match the temperature to the aquarium’s current temp! Use the water change to slightly bring the temperature closer back to normal! Small Steps!!

Temperature Drop Or Rise

For most aquarium owners the water temperature is likely to drop due to the ambient air in your part of the world being cooler than 78-80°F. For those of you that live in the hotter climates and are relying on home air conditioning &/or aquarium chillers, you face a slightly different challenge of keeping your water cool.

Unfortunately, heaters and chiller are serious power hogs and running them on most battery backup systems will run them flat very quickly. Other methods must be used.

Once you have some way of keeping the water oxygenated the next part to survival is keeping the temperature stable.

Lets Split these up:

Aquarium Is Beginning To Cool – There are several ways you can help to keep the temperature warm in your aquarium:

  • Small Aquariums will lose heat faster than large aquariums
  • Wrap warm blankets around and over the aquarium – Just leave a gap in the top for gas exchange
  • Keep the canopy closed as much as you can
  • Keep the door to the room with the aquarium closed
  • Prevent any draughts around the aquarium
  • Warm water on a propane stove or BBQ and place into clean pop bottles to float in the aquarium
  • Run an Inverter off your car battery (Car Running) to power a pump and a heater
  • Remove aquarium water and gently warm it on a propane stove – This is a very last resort. Be careful to check your salinity for evaporation and rapidly adding warm water to an aquarium can kill coral instantly!

Aquarium Is Beginning To Warm – There are several ways you can help to keep the temperature cool in your aquarium:

  • Open the aquarium canopy if installed
  • Open windows to try and create a breeze – Be aware of outdoor dust
  • Evaporation is a great way to cool water. Fanning the water my work
  • Float double-bagged ziplock bags of ice in the water – do not add cold water! You will drop your salinity!

Based on the information above you can see that oxygen depletion is the first killer in your aquarium. To help minimize this we need to get oxygen back into the water and there are two ways to do this:

  1. An Air Pump creating bubbles to help saturate the water with oxygen.
  2. With wavemakers and powerheads to agitate the water surface to enable oxygen to be absorbed and nitrogen and carbon dioxide to be expelled.

Now we just need to find ways to get these devices to work…

What Types of Aquarium Battery Backup Are Available?

To supply battery power to an aquarium there are systems made by aquarium equipment manufacturers to run their brand of pump or filter. You can run off a UPS, an inverter plugged into a car battery or create a DIY battery powered-system tailored to your aquarium setup.

Below are the main types of battery backup systems that are available and popular among the aquarium community, but there are a few things you need to be aware of before deciding on the type of backup system you wish to implement:

  • DC (Direct Current) that is converted to AC (Alternating Current) is terribly inefficient. The units that convert this are called Inverters.
    Your pumps, lights and all equipment that plugs into the wall are AC.
    A battery of any kind only supplies DC so when the system converts DC to AC, a lot of the stored power is lost to the conversion process. This is electrical fundamentals and nothing we can do about it so you have to be aware.
  • Anytime DC is converted to AC the unit doing the conversion (UPS, Inverter) has to manually create the ‘Sine Wave’. This is the way the electrical current flows from the unit.

The Black Line is how a true AC sine wave looks when it comes into your home. Nice and smooth and uniform. This allows motors especially to run properly.

The Blue Line is very square. Almost like an On & Off waveform. this is how the most basic power inverters work and it is very hard on motors and sensitive electronics. You may find your pumps squeal and your equipment does not work correctly when plugged into a cheaper inverter.

The Red Line is called a Pure Sinewave and this is created by using multiple steps to form the waveform. The more steps, the closer the waveform is to being smooth. You will see inverters now called ‘Pure SineWave Inverters’ as these units are designed to run motors and electronics, but they cost more!

Many of the pump manufacturers are becoming aware of this and you can now see DC powerheads, wavemakers and return pumps available from most of the top aquarium brands. This helps running them in power outages far more efficiently and easy!

Here are the main types of backup system being implemented within our hobby:

UPS – Uninterruptable Power Supplies

A UPS is a battery system that is mainly used in the world of computers and IT. The unit plugs into the wall and you then plug in the equipment you want it to run when the power is out.

The UPS will trickle charge while power is available and once the power goes out, the onboard batteries will run for a set period of time to allow you to safely shut down your computer. Having a computer suddenly shut off can create really annoying problems when you go to turn it back on!

A Smart-UPS from APC

Many people may have a UPS sitting around which they wish to use to run their aquarium pumps and that is fine, just be sure to test its ‘Run-Time’ every year. UPS systems are notorious for the batteries suddenly losing their capacity over the years and if you are not careful it could only run for 10 minutes when you next need it!

Some of the reputable UPS manufacturers you may want to look at are:

  • APC
  • Cyber Power
  • Tripp Lite
  • Liebert/Emerson
  • Eaton

Here is a great calculator from APC, one of the world’s most recognized UPS manufacturers to help you decide on what size UPS to buy.
Just add in the total watts of the equipment you wish to run and for how long.

If you can afford it you want to select only the ‘Smart-UPS’ models as these are the ones creating the smoothest Pure SineWave that will be the most efficient for your equipment.

For Example:

2x TunzeTurbelle Stream 1700GPH powerheads( Link)
Input Voltage of each Pump = 120V
Each powerhead draws 12 Watts = 22 watts
I want to run for 8 hours

Just enter these values into the calculator below to get the recommended sized UPC:


For this example, APC suggest a UPS of around 1500VA

This UPS at will work for around $200

Many UPS systems are being used successfully by a lot of aquarium owners and you can instantly see why. You can find some of the most popular UPS systems used by fellow aquarists HERE at

Aquarium Specific Battery Backup Systems

A few of the most well-known brands in the aquarium industry have designed and manufactured their own battery backup systems to either be used solely with their own products or as a generic backup system to be used with other manufacturers’ equipment.

The two main players in the game are EcoTech and Icecap.

EcoTech Marine Battery Backup System

This system was the battery backup that started off the trend of other manufacturers following suit.
The EcoTech Battery is designed for use exclusively with EcoTech’s range of Vortech Wavemakers and Vectra Return Pumps.

EcoTech Marine Vortech Battery Backup
EcoTech Marine Battery Backup

This unit plugs into the wall and your Pump Controller then plugs into the battery pack. It is a self-monitoring, self-charging system that is totally automated, allowing you to Set-&-Forget! Great for when you are away from your home or sleeping!

With up to a possible 72 hour run time for a single Vortech Wavemaker or 30 hours for running two, this system is an absolute must for anyone running or looking to purchase an Ecotech Pump.

EcoTech’s Run Time Estimations

Additional batteries can also be added to create even longer run times, simply by plugging in another battery.
Many people are now buying these to run one for the wavemakers and one for the return pump.

You can find the EcoTech Battery Backup System Here at

IceCap Battery Backup System

The IceCap Battery Backup system is the most versatile system on the market. Pretty much every 12-24VDC controlled pump on the market can be plugged into this system to allow your aquarium water to stay in motion during a power outage.

The kit comes with all the cables and electrical connectors you will need to ensure that your pump/s will be able to connect to the battery system.

The IceCap Battery system is rated to run for 35 hours based on a 50 Watt pump running at 30% power. If you are only running 2x 12 Watt Tunze pumps like in the example above, your battery will last much, much longer!

Just like the EcoTech battery, this can also have additional batteries connected to dramatically increase the run time. It will automatically charge and switch on when the power goes out.
These features make this a great system no matter what pumps you have.

This battery system will only work with pumps that have a controller that they plug into. Any pump that plugs directly into the wall is an AC powered pump and will not work with this system.

So long as your pump is a 12-24VDC pump then you will be able to use it with this, but remember: The Bigger The Pump, The Lower The Run Time.

For those of you that do not own EcoTech products, like me, then this easy to implement battery backup is a fantastic option and one I really recommend.

You can find the IceCap Battery Backup System Here at

Battery-Powered Aquarium Air Pumps

Battery-powered air pumps are great for keeping oxygen levels high in your water during the power outage. If you place the airstone at the sandbed they will also create a small rising current via the bubbles moving to the surface.

If you do not have one of the battery backup systems mentioned above, a battery-powered air pump is a good second place.

There are two types of battery-powered air pump:

  1. Manually Activated
  2. Automatically Activated

Manually Activated Air Pump

This type of air pump is exactly as it sounds – you have to turn it on for it to begin working. These air pumps are great for not only power outages but anytime you are moving livestock away from the main aquarium.

Oxygen can begin to reduce in a body of water in as little as 20 minutes so a small battery-powered air pump is a good investment.

This unit is powered by 2 D-Cell batteries and with good batteries like Duracell, the run time is anywhere from 24-36 hours of continuous use.

You can only connect one airline to this air pump, but you could run that line to a Tee or a splitter to run multiple air stones.

Just be aware the more airstones you run, the more back pressure it will create on the pump and thus reduce its run time.

Marina Battery Air Pump

Having spare batteries ready to go soon cures that problem. Multiple air pumps can be run on the same aquarium if the tank is large.

These pumps are super cheap, but the batteries will cost you a bit more. The major downside to them is that if you are not home when the power goes out these air pumps are useless sitting in the aquarium stand! You have to manually turn them on, even if you have the airstones permanently sat at the back of the aquarium ready to go.

These are some great pumps for a great price to help get you out of a sudden power loss.

Requires 2x D size batteries.

Find the pump HERE at
Find D size Batteries Here at

Automatically Activated Air Pump

This pump takes the Standard D-Cell air pump you see above and gives it automation! The Automatic pump plugs into the wall to monitor the power. Once it senses the loss of power it automatically turns on and starts creating bubbles.

Powered by 2 D-Cell batteries this unit can be permanently plumbed into the back/corners of your aquarium, sitting waiting to run.

Having only one outlet, just like the Marina model you will have to add a Tee or Splitter to run multiple air stones.

You have to make sure that the red switch is in the ON position for it to automatically startup.

With a claim from the manufacturer to run for 48 hours on one set of batteries, most aquarists have never had to run it last that long to substantiate the claim!

This is my preferred choice for a battery-powered air pump as it does not need you to be there to activate it!

Find it out Here at
Find D size Batteries Here at


  • If you have an automatic battery-powered air pump/s permanently installed on your aquarium be sure to test it/them every week by disconnecting the plug from the wall. This ensures the unit will work when required. It only needs to run for seconds to test it.
  • Ensure your air pump is placed higher than the aquarium to prevent back siphoning of the water when it is off.
  • Install a drip loop in the electrical cord to prevent electrocution and fire hazards.
  • If the pump has not been used after 6 months, I recommend you pull the plug and run it fully until the batteries go flat to test its run time and ensure no parts are sticking.
  • When doing your test run, pull your airstones out of the water. Bubbles being pushed around by the wavemakers are not good for fish or coral.
  • Keep multiple spare sets of batteries close-by for easy change out.
  • If your pump has run during a power outage ALWAYS replace the batteries with fresh. Next time you could be away for the weekend and need the full capacity of new batteries to keep your fish alive!
  • Change your airstones every 6 months when testing your pump. They can break down over time and disintegrate.

The Limewood Air Diffusers tend to last longer and resist disintegration a lot better than the ceramic air stones.

You can find the Limewood Air Diffusers HERE at

Are There Any DIY Aquarium Battery Backup Systems?

Tunze Safety Connector

The Tunze Safety Connector allows anyone to build their own DIY aquarium battery backup system for for 12VDC-24VDC Tunze pumps and powerheads. The connector installs between the pump controller and the pump heads and allows the user to connect to 12vdc batteries like those used in cars and boats.

This is an odd name for what it does. The Safety Connector from Tunze is an adapter that allows you to connect a 12-24VDC battery to it and power any Tunze Turbelle Stream Controllable Powerhead or Tunze Wavebox during a power outage.

Most aquarists who set this up use 12VDC AGM Deep Cycle batteries with a battery maintainer to keep the battery/s in peak condition. Many double up the batteries to give even longer run times. Here is the typical wiring diagram:

Tunze Safety Connector Diagram

The more AH the battery, the longer the run time for your pumps. You can easily add in a second battery in parallel to do this as shown in the diagram.

This system is a simple Plug-&-Play for Controllable Tunze Turbelle Stream and Wavebox pumps, but the Safety Connector can also be used to run other manufacturers’ pumps and controllers, You just have to hack the wiring to suit your controller/pump.

For a great backup system for under $200 here are the main parts you will need:

To work out what size AH (Amp Hour) battery you will need you can use this super helpful calculator HERE from, but first, you will need the details below:

The calculator needs the pumps Amperage, but most pumps are given in Watts:-

Tunze Turbelle NanoStream 6055 Controllable Pump
Wattage = 4 to 18W depending on speed ran (I used 18W for worst-case scenario)

Divide Watts by Volts to gets Amps:
18Watts ÷ 12Volts = 1.5Amps

  • 1.5Amps – This goes into the calculator
  • Next Select Hours to Run – eg 24 hours
  • Next Select AGM Battery
  • Hit Calculate

CLICK HERE for the Calculator

For this pump to run for 24 hours I need at least a 72AH 12V AGM Battery like This One Here at

You can find the Tunze 6500 Nano Stream Here at

Inverter Backup Systems

The above system works great if you have any 12VDC to 24VDC controllable pumps, but what do you do if all your pumps plug straight into the wall? The answer is very similar to the above system, except you swap out the Tunze Safety Connector for an Inverter.

A Typical DC to AC Sine Inverter

An Inverter is a device that converts 12VDC from batteries into 110VAC for your pumps to be able to run. For this type of system to work properly you need to pick an inverter with the following characteristics:

  • Pure SineWave to ensure motors run safely & smoothly
  • Automatic switching when it senses a power loss
  • Sufficient wattage to run all your pumps

For a great backup system for around $350 here are the main parts you will need:

Here is a typical Inverter Connection Diagram:

Here is a great little calculator for calculating Run Time of a Battery & Inverter system CLICK HERE

This type of installation requires you to have some electrical wiring knowledge. Always seek professional advice or installation when attempting to install a system like this. accepts no liability for your actions!
This stuff hurts if you get it wrong!

What Can You Run Off An Aquarium Battery Backup System?

Aquarium battery backup systems typically run one or two powerheads. Systems with larger capacity can run DC-powered return pumps, or heaters and lights if designed large enough. The main benefit to battery systems is to automatically keep a pump or two running during outages of a few hours.

When you lose power you may feel like you need to run everything to maintain the health of your aquarium, and while in a perfect world this would be very helpful, but most of us can’t afford the +$20K investment in an automatic whole house generator!

Most of the power outages we face are usually in the region of a few hours to half a day. Any longer than that and you are going to need at generator of some form to keep your tank alive.

If you would like more detailed information about providing emergency power to your aquarium during long power outages please have a read of this article:

How To Keep Your Aquarium Alive in a Power Outage?

We now know that air pumps and water movement give us the best opportunity for survival but what about plugging in other equipment.

Return Pumps

Easy if they are DC-powered and are not large +100W pumps. The more wattage a device pulls, the sooner your battery power will run out. The Controllable DC pumps from Ecotech and Reef Octopus are your best option if you wish to easily add them to your battery backup system.


These are not required to be ran unless you start getting into days without power. By the time you need to run lights for your corals, you will probably have been on a generator-powered system for a while!

Another way you could get light to your aquarium is by reflecting light from a window with a large mirror towards your tank. Even this small amount will help your coral. Fish do not require light to survive.

Natural Sunlight on Aquarium
Natural Sunlight Will Feed Your Corals

Protein Skimmer

Running a protein skimmer is only useful if you have your return pump circulating water to your skimmer. Again, if you have a DC-powered skimmer you could hook up both your return pump and your protein skimmer to one backup system so they work together.


Heaters and Chillers are the biggest power-hungry items on your aquarium! Running at several hundred watts they can really drain a battery quick. Most of the time they click on and off and only run for a set amount of time per hour, but if your home is cold for example, because the furnace has stopped, then your heater will be constantly on.

Aquarium Controller

Having an aquarium controller like the Neptune Apex hooked up to a battery backup system can be really handy to automatically drop the flow rate and thus the power consumption of the pumps it controls when it senses a power outage.

Neptune Apex Aquarium Controller
Neptune Apex Aquarium Controller

The controllers themselves use only a few watts of power so are no major drain on a backup system, in fact many aquarists will put their aquarium controller, internet router and wifi modem on their own UPS or battery backup system so the controller can send you a text or an email to let you know the power is out!

This is super helpful if you want to then get home and fire up the generator so your whole tank (and Furnace 😉 will run.

If you want more information on what Aquarium controllers can do to make your life easier please check out my article about them:

What Is An Aquarium Controller?

How Long Do Aquarium Battery Backup Systems Last?

Aquarium battery backup systems on average will run between 8-48 hours depending on the system installed and the equipment it powers. Powering just a single pump will run twice as long as running two pumps. Run Time = Battery Capacity/Amps drawn by the equipment.

Running pumps/wavemakers off a battery backup can easily give you hours if not days of use looking at the options available. But if you wanted to run more items of your aquairum system? How long would they last?

Its pretty simple math to work it out:

Example #1:
DC Return Pump & DC Protein Skimmer

Ecotech Vectra S1 Return Pump – 55W
AquaMaxx ConeS DCQ-2 Controllable In-Sump Protein Skimmer – 25W
Ecotech Marine Battery = 18Ah

Running off 1 Ecotech Marine Backup Battery with wiring rigged to connect the Aquamaxx ConeS Skimmer:

80W Total Load ÷ 12Volts = 6.66Amps

18Ah (Amps Per Hour) Battery ÷ 6.66Amps = 2.70Hours

Running the Vectra Return Pump & the Aquamaxx Skimmer together will flatten the Ecotech Battery in just under 3 hours!

Run the same pump and skimmer off a Tunze Safety Connector and a 100Ah battery:

100Ah Battery ÷ 6.66Amps = 15 Hours

Add another 100Ah Battery (200AhTotal) = 30 Hours

If you want to run anything but powerheads, you need to have a dedicated Battery Backup system with very large AH Batteries!

Example #2:
AC Return Pump & AC Protein Skimmer

Ehiem 1250 Return Pump – 28W @ 110V AC
Bubble Magnus Curve 7 In-Sump Protein Skimmer – 16W @ 110V AC
Pure Sine Wave Inverter with Battery = 18Ah

Using the calculation from the Inverter Run Time Calculator:

Backup Time = Battery AH x 12V x N x Efficiency of Battery / Load in Watts

Battery AH = Ampere Hour Capacity of Battery
N = Number of 12 V Batteries needed
Efficiency of Battery = Generally it is 0.8, which is the max. power factor of home standard

18Ah x 12V x 1 x 0.8 = 172/(28+16) = 3.9 Hours Run Time

This is a very similar run time to the DC Ecotech powered system.
If you change out the battery to 100Ah:

100Ah x 12V x 1 x 0.8 = 960/(28+16) = 21.8 Hours Run Time!

Example #3:
AC Return Pump & AC Protein Skimmer & 250W Heater

Ehiem 1250 Return Pump – 28W @ 110V AC
Bubble Magnus Curve 7 In-Sump Protein Skimmer – 16W @ 110V AC
Ehiem Jager Heater – 250W
Pure Sine Wave Inverter with Battery = 100Ah

Using the calculation from the Inverter Run Time Calculator:

Backup Time = Battery AH x 12V x N x Efficiency of Battery / Load in Watts

Battery AH = Ampere Hour Capacity of Battery
N = Number of 12 V Batteries needed
Efficiency of Battery = Generally it is 0.8, which is the max. power factor of home standard

100Ah x 12V x 1 x 0.8 = 172/(28+16+250) = 3.2 Hours Run Time!

To run your Return Pump, Protein Skimmer and the Heater (Will say the heater is on 24/7 because the house is cold – worst-case scenario) for 24 hours you will need a Battery Bank of at least 800Ah!

This will cost you $1000 for just the batteries and inverter!

Are There Any Aquarium Power Alternatives To Batteries?

You are better off just installing a battery backup system to run a couple of powerheads for a few hundred dollars and then invest in a good gasoline or propane generator you can hook up and then run EVERYTHING off.

Dual Fuel Generators Are Great Options – Find Some Here at

Be sure to buy one that is large enough to also run your furnace to help keep the house warm in the winter! Happy Wife, Happy Life remember! If your partner is cold but your fish are alive then I can see some arguments starting 🙂

To size one correctly add up all the wattage of the devices you plan to run using the calculations above and ensure the ‘Continuous Use Wattage’ on the generator is higher than your number.

For even more ideas on preparing for a power outage and what to do during and after, I have a great article dedicated to it:

‘How To Prepare Your Aquarium For A Power Outage’

Further Reading

If you are into the techie side of this hobby you might find the following articles interesting:


Hi, I'm Richard and I have been an avid aquarist for over 30 years with a passion for Saltwater Aquariums. I love to pass on my knowledge to help others get the same amount a pleasure out of this hobby as I do. View my About Me page to find out more about me & my mixed reef aquarium.

Recent Posts