What a battery air pump can and can’t do
A battery air pump keeps the water moving and oxygen in it; that is its whole job. It will not run a canister filter, a heater or a light, so plan for heat separately: the lid and a blanket in a cold room and, for a long winter outage, a power station or generator big enough for the heater. A generator runs outdoors only, at least 20 feet from the house with its exhaust pointing away, never in a garage even with the door open: the CPSC warns that one can make as much carbon monoxide as hundreds of cars.
The outage steps follow Florida Sea Grant’s Q&A with Roy Yanong, the UF/IFAS fish veterinarian: aerate, change the temperature gradually, and keep dechlorinated water on hand for partial water changes. When the power comes back after a storm outage, he says to wait a day before feeding, test ammonia and nitrite, change some water if either reads above zero, and clean hang-on-back and canister filters before plugging them back in. UF/IFAS notes that a short pause in feeding does not usually harm fish, except fry, and NC State’s veterinary college suggests a blanket, sleeping bag or newspapers to insulate a tank in the cold.
Our battery backup air pump pages give each model’s power use and battery runtime. Runtime is the maker’s estimate and changes with the setting you run it on, so treat it as a guide rather than a promise.
Pump, airline and air stone
Keep the rest of the kit with the pump: airline tubing cut to length, an air stone or a sponge filter, and a check valve. Aquarium Co-Op’s battery pumps come with the pump, a USB cable and a power supply only. Set the pump above the waterline; if it has to sit lower, put a check valve in the line so water cannot siphon back into it when it stops. Keep the pump and every plug dry, on a shelf rather than the cabinet floor.
Test it before you need it
Run the backup when you set it up and again every few months: unplug it at the wall, check it switches to battery, bubbles at the setting you will use and keeps going, then charge it fully again. Aquarium Co-Op gives about 20 hours of continuous running, or 40 on its power-save setting, for units sold since August 2024; older units list less, and a deeper air stone or a second outlet runs it down faster, so time your own.
Keep a note with the pump: the setting you use, when you last tested it and how long it ran.
When the power comes back
- Clean a hang-on-back or canister that stood still for hours before you plug it back in, as the UF/IFAS vet advises, then prime it as its manual says. Keep a copy of the manual you can read without the internet.
- Check for leaks and that water flows from the outlet.
- Wait a day before feeding, then test ammonia and nitrite, and change some water if either reads above zero.
- Fish gasping at the surface or acting strangely need a water change and a test straight away, and an aquatic vet if they don’t improve.
The battery runtime is a guide for planning, not a safe time for your fish: a crowded or warm tank uses up its oxygen faster.