I have planted as many deciduous trees and shrubs as I could fit along the south and west of my smallish pond (20,000gal) for summer and afternoon shade. I am particularly excited about the PNW crab apples that can handle wet feet and be grafted to any apple we want, and vine maples for their foliage. These also handle wet feet so their roots will be consuming pond nutrients from the pond’s edge. I also have some big leaf maples planted to the west and south of the pond, which have wonderfully bright green foliage this time of year. They are also great ecological stewards, supporting twice their own biomass in other plant species on their trunks when established . This in turn provides them more water storage and nutrients seeping through the moss, which they root into from their trunks. That was a tangent, but my main point would be deciduous trees and shrubs to the south and west for summer shade to reduce temperature and oxygen fluctuations and evaporation.
We have our first of many Ring of Fire biochar kiln burns tomorrow, and at 400gal of char per burn we hope to accumulate enough to create a biochar based filter with a cascade back to the pond for aeration, using a solar powered pump. My main apprehensions are the possible adverse effects of part time aeration (we would not use are backup diesel generator to power the pump during the dark and rainy season), and the degree of evaporation in the summer from moving the water and increasing its surface area exposed to sun. I have also considered just placing “socks” of biochar out in the pond instead for simplicity.