I have a pond that was built in 73 and had no maintenance for thirty years I have about six feet of muck on the bottom. I have been dredging it out with a trash pump. It stirs up some of the muck and causes a nice bloom. I have taken to pumping water down into it to soften the muck up so I can suck it out easier. It does seem to keep the bloom going. It clears up after about a week