Another non-expert here, but in my understanding, 'muck" is partially decomposed organic matter that will continue to desolve naturally if the right conditions are present. Assuming good water quality, the key missing component is oxygen, it's vital to help keep muck consuming bacteria thriving. Oxygen content is usually low at the bottom mucky pond due in part to good bacteria consumes and replaces it with toxic gasses as part of the decomposition process.

If you add good aeration, and boost the process by introducing beneficial bacteria (Muck bacteria pellets). Nature will take of the rest.