Pond Boss Forums INTRO Questions & Observations Painted turtles

All this brings to mind a question I've been thinking about. How many sliders or red ear turtles are too many? My pond is about 2 acres and the fish are doing great. I have been fortunant to have a 6 ft tall stand of saw grass growing all around the pond in the very shallow water and it has served many purposes. But lately I have been seeing a lot of floating grass stems.I am at the pond 2 or 3 times everyday and at all feeding times. The most turtles I ever see at one time is always 4. They are about the size of a dinner plate. 2 years ago I had one, then two,then 3....Are they cutting down the grass stalks? At what point on a 2 acre pond would you suggest thinning out the heard> How many is too many?