Bob, thanks for the input. The pond was 3 or ft low last year. I'd say chara covered a good 40-50% of the pond bottom and it came up to within a foot of the surface. Fishing was virturally impossible, and definetely not enjoyable. It would have been too costly and at the dangerous time of the year to try and kill it off. I do understand about the trade off. We have planted water willow and allowed some smartweed to grow along the shores to help with the uptake of nutrients (and to attract the ducks). Other than some filamentous algae we've never had much of a weed problem other than one other low water year when the chara first appeared. Theoretically speaking though, do you think liming the pond would decrease the chance of chara taking hold like it did last year? Thanks.