I just got in a penn plax b11 battery powered silent air today in the mail...it was only like 12 dollars and it only goes on if the power goes out...i used a splitter so it could run to both of my tanks...i really like it and it is a lot less expensive than the azoo one that runs all the time even though that one is a lot cooler..btw if the power does go out and you do not have a generator is there a trick to keeping the tank heated? any battery powered heaters ? btw hello to everyone