How to Save Your Aquarium During a Power Outage

A power outage can be devastating to a salt or freshwater aquarium. The combination of drastic temperature change and loss of flow and water oxygenation make it one of the worst nightmares a reefer hopes to never face.

If power outage should occur, there are five simple, inexpensive items that can save the day and ensure your fish and coral get through it.

You probably even have some them laying around your house…

1. & 2.  Ice Cubes and a Ziploc bag – the Ultimate Power Outage Safety Combo

Yes, that’s right – ice cubes.  And they are No. 1 on the list for a reason:  ice cubes in a Ziploc bag saved my tank.

ice cubes - a power outage safety net
Ice cubes and a Ziploc bag can save your tank during a power outage!

While my wife and I were away on vacation last month, my worst fear came true – our air conditioner died.  It wasn’t the result of a full-blown power outage – but the results were the same:  because of the hot, humid 90 deg. F Virginia summer weather, the water temperature of my 24g aquarium began to climb dangerously high within a matter of hours…

I instructed my son to FILL a quart-sized Ziploc with ice cubes, make sure it was tightly sealed, and drop it in my sump.  Every couple of hours he check on it and refill it with fresh ice cubes as needed.

It kept my tank temperature below 28° C and saved the tank.

Just be sure the bag you use is tightly sealed and doesn’t have any leaks (So that none of the melted fresh water will mix into your saltwater and lower your salinity.)

The best part is, during a power outage you can buy a couple bags of ice from a nearby store and keep them in cooler until the power has been restored.

3. An Empty Water or Soda Bottle

An empty bottle can be used to either cool or heat your aquarium during a power outage.

We experience occasional 3-4 hours power outages during summer hot spells due to the tremendous burden all the air conditions in our area put on the local power grid.

So, as a safety measure, I keep an old water bottle filled three-quarters of the way with water in my freezer at all times.  If the temp in tank starts to get a little too high, it’s enough to cool for a short period of time.

empty water bottle
An empty bottle can be used to both cool AND warm your aquarium during a power outage.

There is just one with this method of cooling – once it thaws, during a power outage there is no way to re-freeze it once it thaws. That’s why ice in a Ziploc is no. 1 – you can replacing the ice cubes as often as needed until the crisis is over.

When it comes to keeping your tank WARM during a power outage though, an empty bottle can be an absolute tank-saver…

Fill an empty bottle(s) with the hottest tap water you have and float it in your tank. Repeat as necessary to keep the tank warm.

If necessary, you can even use boiling water – just be sure the plastic the bottle is made out of is thick/durable enough to withstand being melted by the boiling water.

 3. A blanket

A blanket can be wrapped around your aquarium during a winter power outage to insulate your tank and slow the rate at which it loses heat.

Used in combination with hot water bottles, it can be a tank-saving combination.

4. & 5. Battery Air Pumps and Air Stones

An aquarium can survive several days without light. But even a few hours without FLOW can be deadly to your fish and coral.  Without flow to continually oxygenate the water and remove carbon dioxide, you livestock will suffocate.

All it takes is few inexpensive, battery-operated air pumps and air stones can keep your critter breathing easy until the power comes back on and normal flow is restored.

I picked up a 3-pack of Azoo Battery Air Pumps for ~$14 from Drs. Foster and Smith to have on hand for my 24g tank…

battery operated air pump
A battery operated air pump with air stone will keep your fish breathing when the power goes out.

But that was before I realized I could get just one that is specifically rated by tank size for just $10 on

Most battery operated pumps come with the airline and air stone. And most run on two D-cell batteries (usually sold separately).

Just drop the air stone into your tank and turn on the pump.

With a few simple items that can be had for under $15, you and your fish can ride out a power outage with relative ease.