I feed frozen brine w/spirulina, frozen blood worms, freeze dried tubifex, discus bio-gold (all hikari stuff) and a custom beef heart i got from my breeder. The bio-gold pellets are the staple, and the others are usually rotated daily so they get 2-3 pellet feedings and 2 other feedings per day. They never get any single of the frozen/freeze dried stuff more then twice a week. My guys are all still young, between 2.5 and 3.5". Also, I only feed the beef heart right before I do a vacuum and WC since it's so messy.
I'd agree with the guys above that regular brine shrimp are somewhat lacking in nutrition, but with spirulina is helps give a nice variety. A high protein varied diet is the best for growing discus