If you want to use no electric from the power company at all you can get a small solar panel a small 12v battery and a 40 watt inverter and a small 3 - 10watt air pump it will run for days on the battery alone the solar cell is just to keep the battery topped off.
If you tank is near a window and gets decent light for at least 5 hours a day this system is viable might even be able to run your lights if they are LED's with that setup as well.
if not then a small air pump with a sponge filter is your best bet.