Here is a link to a little bit of reading that may help until further thoughts come along.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=347862&page=1I do know that in our pond the wife will get leeches on her if she stands and stirs up the edges, but when she uses the dock and goes into deep water there doesn't seem to be a problem.
Reducing muck will help get rid of the places they hang out. That means reducing things that go into the pond as well as clean up what is already there.
