Had a scare mon morning. I had a crazy thunderstorm knock out the electricity. I didn't know how to keep enough oxygen in the tank. I finally decided to use a bike air pump to add oxygen. I attached a air line to the pump attachment and proceeded to pump and produce bubbles. Now I have no idea if I actually added oxygen or not? But, thankfully the electric came back on at 11pm. Phew! The monster zullie is doing just fine. I was afraid I was going to lose him. I am going to buy a battery operated air pump for situation's like this.