Is the water brown from being muddy or is it a "tea" color? Also, do you have run-off coming in from areas that are not covered with vegitation. We have had a lot of rain this year and if you have runoff coming in that is going over non vegitation covered ground that constant addition of muddy water will keep it brown.

If it is "tea" colored it is probably due to tanins from evergreen (in my case hemlock forrest) that will "tea" color the water. I can see down into my pond but it has a "tera" colored hue to it. Gypson will not take care of that. Not sure anything will.