Foam

[MCA]

In your first post you said "but am a bit uncomfortable adding unnecessary chemicals to my pond". Salt is definitely another chemical that does not below in a freshwater pond without a specific purpose. Use salt alone or with some other chemicals to treat specifc conditions.

The only things to add regularly are dechlor products (few things better than plain old sodium thiosulphate ST) and perhaps some other items if you very soft water with very low kh and gh.