QA- thanks for the advice. I think the muck may be more like a foot deep, but from your comments it would seem manageable. Unfortunately my neighbor had health issues recently, so we haven't talked since the original inquiries she made. I will try to reassure her that even if there is a foot of muck depth, aeration would be worth pursuing versus digging out the pond bottom.

On a side note I wanted to share that after operating two aeration diffusers in my pond for about six weeks, that the water clarity is much improved-- easily 24"-- and the algae is on the decline. I continue to rake out FA that I can reach from the bank, but overall the cooler nights and reduced sunlight are shutting down the FA already. What a difference the aeration has made so far. And the fish are noticeably more active around the pond.

From what I've witnessed with aeration in my pond, it would also seem to reduce the quantity of water lilies-- at least within 10 to 12' of the diffuser bubbling. This has been one of my neighbor's concerns too-- the water lilies are covering at least 70% of the pond surface making observation of the fish difficult. I also suspect that reducing the muck via aeration would slow the spread of the water lilies since the muck seems to encourage lily spread and growth.

Thoughts on water lily propagation when aeration reduces muck and the aeration also sets up water currents that pull on the lily stems and leaves??