The problem is predictability of power outage.
A safer arrangement is to have some sort of automatic start up device when main power goes off without warning.
Worst if it happen when no one is at home.
For air pump alone, the AC/DC air pump should be good.
I used to use them, but the problem is after a long time, the build in rechargable battery got inefficient and supply peiod also got shorterned just when you needed them most.
Now a days there is a lot of recycle parts availiable from outdated computer server.
I wonder if one can build some kind of automatic devise from such computer parts (UPS) such that a DC devise ( air pump ) is supply by car battery and when there is AC supply, the battery got charge and is on standby mode, when AC power is interupted the device start automatically using DC power form the car battery.
Appreciate input in this matter.
Cheers!
BT Lee