I would remove the organic debris by hand - more work but you can reduce the "muck" to near zero with an afternoon's worth of your time.

Get a net, reduce the water level by about 3/4ths and then scoop out the organic matter. You can throw that into your compost pile or garden where it can be put to good use.

Unfortunately, I've done that for YEARS but with minimal success. After the first scoop I really just end up stirring up all of the algae that was laying there, and then I'm just flying blind.

Plus, a lot of the gunk just sifts right through the net.

I bought this Muck Reducer and put in the first treatment on Dec 17. It says to do it every 2 weeks, so I'll report back in a few months to update on whether it had an impact.

There is an art to scooping muck without stirring it up too much 😀. Slow and easy wins the race. I turn it into a sort of moving meditation. I clear a section of the pond - wait a few hours and do another section. It is done before I know it. Depending on the size of your pond, that may or may not be possible.

what i do is slowly put in my long handle, fine mesh minnow net and slowly lift out a net full of muck. i only do this a few times each day until i am satisfied with the results. if you do it slow you can keep from catching fish in the net. i empty in a wheelbarrow to check for fish.. the net i use is a expandable net that extends to about 10 ft.

Just wanted to update you all.

I purchased the Muck Reducer that I linked in the OP, and began using it on December 17. The directions say to use 12 tablets for every 500 gallons of water every 2 weeks for "heavy muck buildup"; my pond is just under 1000 gallons, so I used 24 tablets.

I used the last of the tablets today, but I see absolutely no change at all in the muck, debris, or water quality.

I scooped up the larger debris fairly regularly, so this was just supposed to combat the muck that slid through the netting. As far as I can tell, though, it was completely useless.