On a side note, "pods" include several different types of organisms, and many of them aren't even closely realted. Mandarins will usually eat them all. Here's what I found in my tank, in case anyone's interested...
Amphipods: Adults of these seem rare. They can grow very large - many that live under my anemone approach a half inch - though I have found ones nearly double that. They thrive in porous live rock, and their shed skins can often be seen blowing about the tank.
Isopods: The free-living ones are small, and very common. They flourish in the stringy, more ornamental types of hair algae. They also seem to grow well on cyanobacteria mats (they dot it's surface). These are probably your best bet for mass culture.
Copepods: The ones I have found in my tank are even smaller than the isopods, and comparatively rare. I'm not sure as to what habitat they prefer.
Flatworms: Common, and slightly bigger than copepods. As with all microfauna, they will grow and reproduce faster in an overfed tank.