I considered the addition of filtration for that same reason; I wanted to see the fish. The first few years of operation my pond was always pea soup for much of the summer, often clearing perfectly as fall approached. But the past couple of years my water has stayed algae-free and clear all summer. It's been lovely! I think it is because the plant life has grown in and is now outcompeting and also shading the algae. It's great to be able to watch the fish.
As much as I am a fan of water changes...I don't do any in the pond. It gets a once-per-year change of probably 80-90% in the spring; I pump out most of the water in spring as soon as it thaws, and most years it fills itself up from snow melt, as I normally have literal tons of snow I can throw in. If the thawing and melting is poorly timed or it's just too dry a spring (a rarity) I will fill it from my well.
When I added the airstone that powers my bog filter recirculator, I found the bubbling to be a very unpleasant commotion after years of calm, still water. I think this year I will be concealing and capturing those bubbles with some kind of cover or "bubble corral" so that they don't disturb the surface; they were harshing my mellow...
