[greenbean36191]

There is no free lunch. You could install a turbine and get energy back from it, but there's no such thing as 100% efficiency. You would be taking electrical energy, converting it to mechanical, then back to electrical (and then presumably either to mechanical or light) with losses at each step. You get back a lot less energy than you put in. The turbine would decrease the flow, so in order to get the same amount of flow you originally had, you would have to increase the wattage of the pump by more than the wattage put out by the turbine. If the lower flow doesn't bother you then it would still cost less to just run a smaller pump than it would to run the current pump, with the energy reclaimed by a turbine.