Sump pumps are not designed for continuous operation only intermittent duty. The pond liner track record speaks for itself: More than 37% of all waterfalls have serious structural damage within 3 years of construction, 57% of homeowners say they are rather unsatisfied with the way their waterfall came out after the project was completed, one in three waterfalls and ponds are leaking water within nine months of completion, and 63% of "do-it-yourselfers" say they wished they had the proper information from the "get go" or that they had hired someone.
Here is a summary of what I tell these people whom I have helped:
A water garden should not be considered a short term investment. The friend investigated and discovered the contractor had installed a mechanical water level controller to the pond. It was full of algae and smelled like dead fish