Pekins are poop factories. Depending on how big your pond is, it could possibly make a difference getting them out of the pond. At .5 acres I think it could make a difference.

The other "problem" with allowing pekins to "free range" on a pond is that they can breed with wild mallards and produce fertile offspring. Pekins, like most domestic duck breeds came from selective breeding of mallard stock. A notable exception to this is the muscovy duck. I always worry about diluting "wild" breeds. Perhaps it's overblown, but it's always been in the back of my mind.

12 ac pond in NW Missouri. 28' max depth at full pool. Fish Present: LMB, BG, RES, YP, CC, WB, HSB, WE, BCP, WCP, GSH.