1.  Field of the Invention
The present invention relates generally to fluid pumps, and particularly to a multistage pulsating airlift pump incorporating two or more airlift pump stages that communicate with one another electronically to time their outputs for increasing the total lifting action of the assembly. 
2.  Description of the Related Art
The conventional airlift pump is a simple device, comprising a discharge or jet of air or other gas into the lower end or portion of a substantially vertical standpipe situated in a body of water or other liquid.  The air or gas jet entrains the liquid and raises the liquid within the pipe to expel the liquid from the open top of the pipe, or from a discharge pipe or tube extending from the top of the pipe.  Relatively small solid particulates (e.g., sand and gravel) may also be lifted from the bottom of the body of water, depending upon the energy in the airstream and other factors. 
A problem with conventional single-stage airlift pumps is that they are incapable of lifting or raising a liquid to a substantial height or head above the surface of the liquid in which the pump is installed.  Accordingly, airlift pumps are not conventionally used in applications requiring significant lifting of a liquid, as in deep water, oil wells, and the like.  While it is possible to use a series of airlift pumps in such applications, such devices have generally been configured as separate units, where the liquid lifted in the first stage is captured or trapped and then lifted again by a higher second pump operating essentially independently of the lower first pump. 
Thus, a multistage pulsating airlift pump solving the aforementioned problems is desired.