My tank is 280 litres and holds 1 Yellow Tang, 1 Scorpius Tang, 2 Blue Tangs, 2 Perc Clowns, 1 Blue Line Clarke Clown, 1 Flame Angel, 1 Lunar Wrasse.
They get Tetra marine flake every day or second day and 1/2 a sheet of nori. A piece of rock with algae grown on it about onces a month. I only feed 1 type of dry food at a time as it take quite a while to get through even a small containers. The tangs are really pandered to with feeding , keeps them nice and fat and growing - nothing worse than skinny tangs.
Tell your LFS to give Biosuppliers in Auckland a call. They can order the Mysis shrimp from them and only have to by a box of about 10 at a time.