well I plan to put in a 10" syphon system as this would not require us to further drain the pond. The pond is so low because the cast iron pipe had rusted through at this level. On the pond side-I plan to put an 8" PVC sleeve over the cast iron pipe to about 2' above it and fill to the top with concrete. Haven't come up with a real good idea as how to plug the old pipe on the discharge side yet, any ideas?