Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Need Help Identifying

That dark crap looks like dead organic particulates in various stages of decay. It floats probably because of the gases produced from the decay. Ponds are always, constantly in the process of change depending on what is in the pond and what is getting into the pond that eventually results in some sort of growth that usually dies and decomposes. Ponds are composed of numerous internal complex interacting systems same as the human body - always changing. Right now your pond appears to be puking from too much of something.