These are some of my sugestion
a coarser bottom meterial would probaly be better like sand or pea rock
Bottom feeding fish are likely to stir and lossen bottom
Some Aquatic plants to keep nutriants down and slow algal blooms (Possibly in a pots )
Seal pond with bentonite clay mixture to insure minimal water seepage ( also know as Well drillers Clay)
would use a Air stone Bubbler for areation and keep areator off bottom ( some run off a small wind mill)
just one example I found randomly( www.windmillaeration.com)