Just a thought. If raking seems to improve muck elimination then would that seem to suggest that composting is taking place by adding dissolved oxygen and mixing like the composting that takes place for gardening? And would adding KOI carp that grooms the bottom also aid in the mixing of the bottom muck. To test this thought out the next time I go kayaking I know of an area where the carp are very thick and so I will test the bottom for muck. The down side of the large number of carp is the water is very muddy.