If a pod was going thru a pump, I could see it possiblyygetting chopped up more easily as opposed to very tiny microscopic critters such as their off spring and the other small stuff ...I think there is a name for the stuff that grows around tand on the macro algaes and sea grasses, I want to so epithelia... or somethin like that , they help to sustain the zoo planktons etc...??? In the end, it is not really an issue, they are really pretty small, not like a fish going thru a turbine ....
Mandarins sometime do take mysids, blood worms, brine shrimps etc... I would not rely on a refugium to supply all the food, unless it was like 3x the size of your tank, and even then I am not sure that would keep up with the mandarin and everything else that eats all that comes out of a refugium...
Denise