I picked up a piece of aluminum at the steel surplus shop and mounted the fish feeder.
I have an air stone in the fish tank from my DWC air pump. So if the water pump impeller goes bad the fish will still get air.
I connected up my contractor that has a normally closed contact. I connected my 12 volt dc air pump through the contactor. This is connected to a 12 volt car battery that is changed with a solar panel.
So as soon as my other air pump/water pump has lost power. This 12v dc air pump will start pumping air and as soon as the power comes back the contactor will take power away from the 12v air pump and it will stop.
Backup air supply operation
12v power supply for the relay/ contactor hooked 120 volt AC power to A1 and A2.
The red wire to the pump will go to 21 and the positive side of the 12v batty goes to 22 the normally closed connection.
A1 and A2 120 volts AC
21: pump red wire
22: battery + 12 volt (a fuse is close to the battery)
Battery black – goes to pump – black side.
The contactors are used to run elevators and are very robust.
21,22 are the normally closed contacts so when 120 volt AC power is applied it will open the contacts.
Then when we lose power it will close the contacts giving power to the air pump.
Now even if I am away from home and we loose power the fish will still get air.