How do I get rid of sludge in the bottom of my koi pond?

Question

IT IS 3500 GALLONS, FULL SUN, 3 YEARS OLD, BIOFALLS AND SKIMMER FILTERS, NOT MANY FISH, CLEAR WATER. THE SLUDGE SEEMS TO SINK INSTEAD OF FLOATING INTO THE SKIMMER FILTER. I HAVE TRIED SLUDGE AWAY AND BACTERIA.

Answer 1

SHOULDN'T THE GOLDFISH BE EATING THE SLUDGE?  MAYBE YOU NEED MORE FISH

Answer 2

Do you have any plants in your pond?   Maybe some root action would help.  If you scoop it out, do you get more right away?  If you do, you are overfeeding.