To feed or not to feed

Hi all. I just found this newsgroup, and being the owner of a
relatively new pond, look forward to participating in it for awhile.
My question, we have a 1,000 gal pond with about 11 goldfish in it.
(We stocked 12 but one didn't make the transition). We live in
Roseville, which is just outside Sacramento, CA. It gets into the 100's
in the summer and down to the 40's in the winter, with a few nights in
the 30's. Should we feed the fish once-in-awhile or let them eat
whatever floats into the pond? I'm concerned that fish food might
promote algae, which during the cool winter is an ongoing problem, but
I'm also concerned that the fish may not find enough to eat, too.
FWIW, the equipment is from Aquascapes and I regularly spike the pond
with the algae eating bacteria they sell. I'm thinking of buying their
liquid, as opposed to powder, bacteria. It's more quickly acting than
the powder.
Thanks!

Bill