Wow! Thanks for all the great advice.

The pond is around 1,000 - 1,200 gals with a 3600 gph pump. The return is a
3 inch rubber tube buried under a few inches of dirt. Over that there is a few
hundred pounds (no kidding) of rocks. The waterfall is about 6 feet above the
pond level with 6 tiers. The pump in the skimmer goes straight into the return
tube. There are 13 adult goldfish in the pond with about another 10 fry (and
counting) swimming around with the others. (They haven't taken on a gold color
yet, though you can just see hints of it now).
Today, the water got to 82 degrees, which seems a bit too hot. From what I've
read, the highest water temp for goldfish is around 76 - 78.
Right now the pond has no shade. There are water plants that provide some
shade but not much.
Sounds like the best thing to do is set up a light colored tarp to shade part
of the pond. Now I've just got to figure out how to do that.
Thanks again.