I layman's terms no, the net gain would be at best 10% of pump input (a guess), friction losses of the water falling over various ornamental object uses up most of the energy.
If you wished to include a small water turbine as part of the water path and run a few LED's then yes it is possible, but would never recover the power required to pump the water. But be warned! should you follow this path you may become addicted to making power.
allan down under