Sounds like the pond has inherited a natural balance in the eco system
with each other. However odds are it will go sour on you some time or
other once just a single thing gets out of line. To me its usually
easier to keep things up by checking and doing odds and ends than
having to fix a major problem when remidying a simple problem would
have eliminated the major.

I assume you live in the southern portion of PA if your not concerned
much with any major winter issues and freezes, but don't
underestimate momma nature.

I like the beach umbrella idea myself......I have a small approx 8 or
10 gal preformed pool which was made for use as a connecting pool,
instralled in the middle of the companion plant section of our water
garden into which I continuously pump water into from out of the large
natural pond. From this connecting pool it flows out the spillway
through a small stream and over a waterfall. Even though its
constantly getting fresh cool water from the depths of the large pond
I still use an umbrella to help shade the little pond, until some of
thre companion plants get large enough to do it naturally.

If there are sufficient insects then supplemental feeding may not be
needed.
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