Power interruptions are a fact of life. While some people may never experience one, most of us will, and it will pay to be prepared. Even if you’re an experienced aquarist with many years of success, my hope is that some of these ideas will be novel and provoke innovative thinking. With preparation in mind, here are some tips that could be useful.

Assess the Risk
Develop an understanding of the types of power outages you are likely to face. Good risk assessment and management will not only increase your chances for success, it will also help you determine the scope of preparations required. If you live in an area prone to hurricanes, tornadoes, earthquakes or blizzards, chances are you will face an extended power outage. People in other areas may only face power interruptions of four hours are less. Know your situation!

Power is Everything
The sun powers all wild reefs. From ocean currents to wind to warmth, the sun is responsible for the existence of tropical reefs.


photo credit: Mike Harris & Marni Friesen
Consequently for captive reefs, electrical power is our substitute for the sun. Electricity runs the lighting, the heating, the water circulation and oxygenation, and many other processes that transpire seamlessly in everyday reef keeping. Quite simply, without power, the reef dies.


R2R member @Olddude's beautiful reef

Not All Power Interruptions are Equivalent
In lightly stocked tanks in temperate climates, a power outage of 2-4 hours may be of little significance. In hot or cold climates with heavily stocked tanks, the situation can become critical in an hour or less. Understand your system’s biological oxygen demand and rate of temperature loss or gain. By contrast, lighting is much less important. I’ve always prioritized in the following order from most to least importance:
  1. Oxygenation (water circulation and aeration). Oxygen levels can become depleted in a matter of hours or even minutes. Water circulation always gets top priority. If you can spare the power, consider running your skimmer on backup power. Combined with circulation, the oxygenation provided by a skimmer or battery-powered air pump will give you time to think or engage your backup plan.
  2. Temperature. For smaller tanks, temperatures may change rapidly and could be as important as oxygenation. Fortunately for smaller tanks, neither temperature control nor oxygenation require a lot of power so there is no real need to prioritize between them. For larger tanks, however, the rate of temperature loss or gain is much slower due to the heat capacity of water. One hundred or more gallons of water require a significant heat input or removal to cool down even a couple of degrees. Considering most reef organisms can easily tolerate a temperature change of 2-4 degrees over four or more hours, I’ve always given secondary priority to temperature. Admittedly for a system in a colder climate with electric heating, temperature loss is as important as oxygenation. In colder climates, temperature conservation may be obtained by wrapping the tank in blankets or other insulating material. It bears repeating—know your system and the types of outages you are likely to face.
  3. Lighting. Finally, there is lighting. Given that it is not uncommon for aquarists plagued with dinoflagellates to completely black out their tank for three consecutive days, it follows that lighting is less important. If you can spare the power to operate lighting, fantastic. If you’re on a budget, I would not spend money on backup power for lighting unless I absolutely knew that I could face power outages in excess of three days.
Keep in mind not only is power everything, but also the name of the game is to outlast the power interruption. Outlasting the outage generally entails what I call “running the clock out.” When you run the clock you, you are trying to maintain basic life support systems longer than the duration of the outage. While that means your tank may not operate normally, it also means that you can shed electrical loads to conserve power and extend the length of outage your tank can survive. Keeping tank inhabitants alive is the name of the game with power outages, and many times this can be accomplished with only a fraction of the power a system typically consumes.

Have a Plan
Once you understand your system’s particular power requirements and have prioritized them accordingly, you can begin to determine the type of backup power you will need. Most modern equipment will have the rated power consumption readily available on the packaging or labeling. For those that may not be familiar with it, power consumption (P) is equivalent to a device’s operating voltage (V) multiplied by the amount of electrical current (I) it draws while in operation, or:

P = V x I

Consequently, most of the equipment in domestic aquariums runs either directly off of 120 VAC power or 12 VDC power. Both direct and alternating current devices follow the power dissipation law stated above. A device with a power consumption of 100 watts will consume 100 W/120 VAC or 0.83 amps if it is a 120 VAC device. The same load operating on 12 VDC will consume 100W/12 VDC or 8.3 amps! Sum up the power consumption of all devices you intend to run on backup power, and you will be well on your way to sizing backup power options properly.

Backup Power Options
There are many options for backup power. I’ve tried to list some of them below in order of increasing cost and complexity.
  • Battery-powered air pumps. These pumps are cheap and can be very effective on smaller systems. Some models like the Silent Air B11 from Penn-Plax operates on backup batteries only when the main power has gone out. While low cost, this may not be the most effective solution for larger tanks and several may be required to maintain proper aeration and circulation in a larger system. You could also consider some of the 12 VDC aeration pumps used in saltwater live wells on fishing boats. Price is less than $20-40 per pump, depending on the type selected.
  • Long extension cords. While this might sound ridiculous, it may be all that is needed when you have neighbors nearby and your house is the only one affected by a power outage. Under these circumstances, it pays to know your neighbors and be on speaking terms with them! While not a likely scenario, the long extension cords can also be used in some of the other options listed below. Depending on the length and gauge of extension cords purchased, pricing is typically less than $100. You can purchase these at your local hardware store or online.
  • Dedicated battery backups. This option can take a couple of forms.
  • In one instance, a simple 12 VDC sealed lead acid battery and an inverter can be used to power equipment in an emergency. Depending on load, the battery may last several hours to days. If you choose the inverter route, select a model that can be used with both the standard 12VDC cigarette lighter socked in cars and can be used with 12V batteries.
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    For equipment operating on 12 VDC, IceCap and Ecotech both make a battery backup that can run powerheads or return pumps. Read the fine print as not all battery systems are compatible with all pumps. Price is typically less than $200 per unit or battery/inverter pair.
  • Standard computer UPS systems are also available and can be used to power critical electronics like controllers and other monitoring equipment. A 1500VA UPS system will operate a 100W load for 60-90 minutes, depending on the age and condition of the equipment. Many nice units are available for $150 or less.
  • One final note of caution. If you are going to use unsealed 12V batteries as a source of power, make sure you use them in well-ventilated area. Unsealed batteries can leak hydrogen gas when charging and can spill sulfuric acid, so a little forethought into placement goes a long way.
  • Gasoline Inverter. There are small gasoline or dual fuel inverters that would easily power an aquarium for an extended period of time. Generally, these units produce between 500 and 1000W, more than enough power for most circulation and heating systems. Try to find a system with low harmonic distortion or couple it with power conditioner to ensure sensitive electronics are adequately protected. Some inverters and generators do not produce a clean sine wave and can damage aquarium controllers and other components. Power conditioners will ensure that the power quality is acceptable enough to avoid damaging equipment while on backup power. Price is typically less than $300 for a gasoline inverter and power conditioner.
  • Generators. Similar to inverters, these are the beasts you think of while camping or following a landfalling hurricane. Power quality can still be an issue unless you purchase a high-end unit, so the same power conditioner recommendation applies. Price is typically less than $1,000.
  • Whole House Generators. Probably the Cadillac of all options, whole house generators can not only power your tank but potentially your entire house for an extended period of time. However, in areas where natural gas service is not available, LPG or diesel/gasoline options are available but at the possibility of reduced run times. Expect $5,000 to $10,000 or more for this option, depending on size or complexity of the system you choose to install.
Please keep in mind that the linked products above are not an endorsement, but the information is provided to allow the reader some familiarity with the types of equipment mentioned in this article. There are many quality brands available that will do the job, and some of these items will not be in all areas.

Other Options
Remember, the name of the game is to outlast the outage. With that in mind, there are frequently other ways you can extend the backup power in extended outage scenarios. For instance, suppose you have a 12 VDC battery and a 500W inverter. The rough runtime for a 100 A-h battery with a 300W DC load is approximately 2-4 hours, depending on battery type and condition. When the battery is dead and the main power is still out, what else can you do? In this circumstance, you could run that long extension cord to your best neighbor’s house if the situation warrants it, but that’s still an unlikely scenario. You can also have spare 12 VDC batteries available or you could rob the battery from the family vehicle. It is possible that you could ruin the starting battery for your vehicle in the process, but that is still WAY cheaper than crashing a large, well-established system. Another option if you have a newer vehicle is to utilize the built-in inverters that many vehicles have today. Use that long extension cord to supply power to critical systems from the vehicle. Most vehicle systems have power limitations on their inverter systems, so make sure you prioritize your load accordingly and observe maximum power draw constraints. You can even start the vehicle to extend run times as long as it is parked in an area with adequate ventilation. Finally, ALL 12 VDC batteries can power an inverter. Batteries from riding lawnmowers, motor cycles, and especially deep cycle boat batteries are prime candidates to extend the runtime of critical life support systems.

Prioritizing and Shedding Loads
You can prioritize power and shed electrical loads according to what I call “the desperation factor.” I typically develop a plan that utilizes load prioritization to extent runtimes. For instance, in the first hour or so, I just let the UPS and Apex manage the situation. The Apex is programmed to shed nonessential loads automatically upon loss of power detection. However, this strategy only works for the first hour or so due to the limited amount of stored energy in the UPS. I have a dedicated battery backup for one of the power heads that operates independently from the Apex/UPS system, and that will keep water moving for several hours. After a couple of hours, though, it’s time to get serious. I have a DC inverter and several deep cycle 12 VDC batteries that I can use to power pumps and the skimmer. After that, I would break out the generator to supply emergency power. I keep spare gasoline on-hand, but gasoline in vehicles, boats, mowers and other equipment is also fair game if the situation is desperate enough. If all of that fails, the situation is really dire. I would choose to shed the skimmer load and keep the circulation pumps running by utilizing the 150W inverter in the family van, and I’d start begging neighbors for gasoline. While not the same plan you might employ, this exercise underscores the importance of having a plan with multiple backup layers. You should carefully consider what other actions you could take if each layer fails in succession.

Variable Power Devices
With the advent of controllable DC devices like pumps and skimmers, keep in mind that this also affords an opportunity to shed some electrical load. While not ideal under normal circumstances, you can operate variable speed power heads and return pumps at a lower power draw to extend the runtime of your backup systems. Many times, you may be able to reduce the power consumption by 25-75%, depending on how the device is typically run and given the particulars of your setup. Experimenting with those devices while the power is on will allow you to know ahead of time how far the power consumption can be trimmed during an outage scenario.

Apex Setup for Power Loss

If you are utilizing a Neptune Apex for aquarium controls, I strongly recommend you setup the Apex to monitor for power outages and shed loads according to your predefined plan. The Neptune Systems website has more detailed instruction on how to implement this setup, but suffice it to say the configuration involves a separate 12VDC power supply and some code modifications. For every device that is non-essential, the following line of code can be inserted into the control syntax:

If Power Apex Off 000 Then OFF

Consequently, the “OFF” command can also be changed to “ON” to ensure those critical devices are powered.

Testing and Maintenance of Backup Systems

Finally, testing and maintenance of equipment is an absolute must to ensure proper functionality during those times of emergency. Batteries should be charged and generators should be run periodically, UPS and battery backup batteries should be changed out every 2-3 years, and there should be an ample supply of batteries available for devices like battery-powered air pump.

Test your Apex to ensure it properly shed loads, and monitor UPS systems during the next power outage to gauge the amount of time the UPS will last with your current system configuration. Give some thought to where you might be able to park the car if you need to run one of those long extension cords to the on-board inverter, and keep a healthy, preserved supply of gasoline for generators and other devices. Use a stabilizer in your gasoline to extend shelf-life, and rotate your gasoline stock on a periodic basis.

Parting Shots
While not intended to be an exhaustive list of possible methods for surviving a power outage, I hope that the above thoughts will spark new ideas on how to outlast the next power interruption. Having a plan, preparing ahead of time, and testing and maintaining your backup systems will go a long way to bridging the next power interruption. Get creative and you may just develop additional, novel ways to ensure your aquatic inhabitants are around for years to come!