How to make a simple bubble-pump.
I'll be using this to feed a window-garden... more on that later.

Here's a link to the pump working

http://www.youtube.com/watch?v=kTnRSsDEO9w

Materials

Vinyl tube
An IV infusion kit
An aquarium air pump

Costs

<$10

Time

< 1 hour

Step 1: 1

You'll need two things to make this pump... a length of pipe and an IV infusion kit.
After you cut the pipe to your required length + 1 metre, there are no other adaptations required. You don't need to add anything to the vinyl pipe or make changes to the IV infusion kit.

Remember, if you want to pump to 4m high, you'll need 5m of pipe.

Step 2: 2

1 metre from the end of your vinyl pipe, place the needle of the IV infusion kit through the pipe wall.
Point the needle in the direction of the intended flow of the water... i.e. away from the closest pipe-end.

Step 3: 3

Coil the 1m of pipe in the bottom of your water reservoir and add a weight to the pipe around the point where the air-needle enters the vinyl pipe.

The idea is to introduce the air into the vinyl pipe at the bottom of the water tank.

Your first 1m of pipe and any further submerged pipe should now be full of water... if it isn't, then suck start a siphon process from the 4m end of the vinyl pipe to clear air from the system, then reposition the top end of the pipe again. Make sure that the submerged pipe is all flooded.

Step 4: 4

Introduce air to the IV infusion kit at the other end. Connect a pipe to the aquarium air pump here.

When you first start the aquarium air pump after following this Instructable, set the inline choke on the IV infusion kit to maximum flow - and when the water moves upwards in the vinyl pipe, slow down the airflow using the choke until the air speed is at a strength that doesn't quite destroy the moving plugs of water in the vinyl pipe. For maximum flow, the plugs of water should move quickly... almost too quickly to see them cearly.

The pump will self-start after the first manual start. No problems with restarting after power outages or downtimes if the pipe in the tank has not been disturbed - just repower the air pump and it'll work.

Problems 1. Too much air and the pump won't work because plugs of water cannot form and then rise inside the vinyl pipe - the force of the air destroys them.

Problems 2. Too little air and your coiled 1m of vinyl pipe in the bottom of the water tank will allow the pumped air to escape down into the water tank rather than climb upward... this is due to lack of back-pressure counterbalancing any rising water contained in the vinyl pipe at low air supply pressures. If you need a slower delivery of water, then use a longer coil of submerged pipe to give better back-pressure and stop air escaping "backwards"..

That's it.

Job done.

Your pump should now be working.