Save some money and go to the grocery store. Go to the seafood section and buy some fresh, unprepared seafood (shrimp, clams, crab, fish, squid, octopud, etc). You can chop this up very finely and feed it to your frogspawn by just turning the powerheads off for awhile and dropping the food onto it.
This is much cheaper than buying lfs coral food, it is better for your corals, and you can freeze it and save it for later.