This pulser pump is made from a discarded plastic soda bottle, an aquarium air pump , plastic tube, pieces of an inexpensive plastic kerosene pump (hose and check valve). It can be permanently assembled together using 'goop' or something similar- though the one in the pic is just 'jammed' together.
The soda bottle is cut off close to the bottom and a piece of air pump plastic tubing is pushed thru a small hole near the now open bottom. The tubing can be heated a little at the end to make it flare out. The other end is attached to the aquarium air pump. The kerosene pump outlet tube is removed from the remainder of it along with one of the plastic check valves. The outlet tube is larger at one end and the check valve jams into it. this assembly is then puled thru the open neck of the plastic bottle (wedged thru). The assembly need be weighted to hold it down in the water when it fills up with air. For a temporary one I used a pair of vice grips-feel free to experiment. On a smaller scale you could remove a tirevalve stem core and then remove its spring for a 1/4" tubing size one way valve...
Principle of operation- the air pocket formed in the bottle forces the check valve open when the weight of water that is displaced by it -is more than the weight of water above it. It then allows the air to be pushed up by water- the velocity of the water sends it up the outlet tube. It has better performance than a conventional bubble pump.http://www.youtube.com/watch?v=HYa757JZGpM
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