Here is a picture of the whole setup, showing the fishtank, the settling bottle and the air pump.

This is a diagram showing how the whole system works.

The air pump.

This is a picture of the bubble chamber. There are rocks in the bottom of the bubble chamber for ballast. You can see the air coming out of the top of the straw.

Because I don't use an airstone, the top of the water churns pretty heavily.

Near the front of the tank you can see the water return line that siphons water back into the settling bottle. The sediment on the bottom of the tank is due to the fact that I had not maintained the tank for a while. You can see a fish in front of the water return line. The plants in the tank were recently added. They are mostly for the fish to eat. They won't last long, because they won't get enough light when the curtains are closed.

This is the top of the settling bottle. This is actually the settling bottle from the setup I have in my children's room. Notice the two hoses, one feed line and one return line. By tracking the speed of particles flowing through the line, I have calculated that the system moves 25cc. of water per minute. That's 1.5 liter per hour, or 36 liters per day (about 8 gal.). My tank is a 2 gal. tank, so the water gets changed out about 4 times a day!

These are the water plants I use. I don't know what they are called, I got them from the pet store (cheap).

This is the bottom of the settling bottle. Notice the snail (dark spot in the middle). These guys cruise around and keep all the surfaces clean, but they eventually clog the tubes and must be cleaned out. Also notice the sediment in the bottom.

A gratuitous picture of my fish. They came from a ditch down the road from my house. They are hardy, tolerating neglect. They are small, generating little waste. They are also free.