String Algae Invasion

Hi -

I went on a five day vacation, and while I was gone it was hot (like 90
degrees, So. Cal).

When I got back, I had string algae all over - down the waterfall, in the
pond, the fish were freaking out, etc. I mean, this stuff was everywhere.

This is my first spring, the pond went 'live' last September. What should I
do, I've never even seen string algae until the past two weeks!