Pond Boss Forums AERATION Systems questions Pond areation.

Bottom diffuser aerators installed properly should not stir up bottom muck. Bottom aerators should be separated from the muck with a plate or some sort of shield or be placed above the muck on a stand or frame. Bottom aeration best used keeps dissolved oxygen on the surface of the bottom muck so oxygen consuming bacteria can relatively quickly digest the organic sediments.

The plant looks to be one of the floating leaf Potamogeton species maybe P. gramineus as Variable pondweed. A little later in the summer the plant should produce a seed head slightly above the surface.
https://aquaplant.tamu.edu/plant-identification/alphabetical-index/variable-leaf-pondweed/

Better description
https://www.minnesotawildflowers.info/aquatic/grass-leaved-pondweed