Short Answer:
Use a combination of aeration, beneficial bacteria, and organic matter reduction.

Detailed Answer:
Muck is decomposing organic material (leaves, algae, waste).

Effective methods:

• Aeration → adds oxygen for decomposition
• Beneficial bacteria → accelerate breakdown
• Reduce inputs → leaves, runoff, waste
• Dredging → for severe buildup

Important:
Bacteria work best in oxygen-rich environments—aeration is critical.