I was swimming in my pond yesterday. It has bottom diffuser aeration and is pretty chilly top to bottom due to the mixing action. When I didn't have aeration, at least the upper layer was warm. My priorities are Fish, looks, then swimming so this is fine for me.

Most fountains don't mix water as deep as bottom diffusers do.





"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge." Stephen W. Hawking