Keith,
Did you say a "2500 sq ft" pond? Sounds like a backyard water garden to me. Is that an accurate statement? If so, I don't work on ponds that small and you may want to speak with a water garden specialist. For that size pond, fertilization may not be a good idea. Even if you did fertilize, you'd be using about 4 oz of fertilizer from a 25 lb bag.
Not sure if I'm on the same page as you.
Just my $0.02.
