Penn-Plax (2 Pack) Silent Air B11 Battery Operated Aquarium Air Pump for Power Outage Automatic Turn On Keeps Fish Safe Up to 29 Gallons

Works great for reef tank during power outages

The media could not be loaded. Works as described. Insert two D batteries and youre pumping air when your power goes out. Not so silent, as you can tell from the video.

I know nothing abut this stuff, but nephew did and loved it

I have 4 of these units. First, as many have written, the "silent" in the title is a joke. They are loud. But more importantly, when the power goes off, a couple my not start until the reset button is pressed. This isn't helpful if you're out and the power goes off.

I've got one in each aquarium just for backup if we're gone during a power outage.

Great product! Am be buying a second set! They immediately begin pumping air into tanks the second the electricity stops! I love knowing that my little fish friends haveTheir owm little back up generator in case of brown outs!

Got the 2 pack & the 1st one I opened didn't work so I returned both.....

I like that they are trustworthy. They are loud when they come on. Every time I have had a power disruption since owning them,they have did their job.