If you haven't done this take some time and read this from the CommonQ&A Archives:
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=92639#Post92639

I've sold numerous pond aerators and showed people how to build them since 1985. I allow them to bring the aerator back for a full refund if they don't think it helps the pond. So far no one has returned an aerator. If for some reason it stops working, they quickly get it fixed or call to correct the problem since they continually see beneficial results from pond aeration.


aka Pond Doctor & Dr. Perca Read Pond Boss Magazine -
America's Journal of Pond Management