Thinking of getting one of these, but not sure how they work. Do you have to connect them to anything? Do they need to be plugged into the electricity?
Air stones work but connecting them with an air line (long thin flexible hose/tube) to an air pump (which yes, needs to be connecting to a power supply). The pump is kept outside the aquarium.
You would still need to buy the pump and tubing. I have a tank that's 30 inches long so I bought a bubble wand that's about 14" so it takes up about half the tank. I also have a Tetra Whisper pump and the tubing. Here are the average costs of these items:
14" bubble wand - $7.99
Pump - $17.99
tubing was about $12.99
Oh well, that one's on hold then. Just spent £100 on filter, heater and cabinet for the new tank, and it needs new lighting more than it needs an air stone IMO.