I've had great success with setting up a 50g DT and a 25gal sump with podes and have a thriving Mandarin. He eats all day and I always see pods climbing all over the glass in both the DT and the sump.
I filled the sump with rock rubble, a couple balls of chaeto, and a few clusters of empty barnacles. The chaeto already had copepod populations in it, but I added two bottles of Algagen copepods while the return pump was off. I let the sump sit for abotu 1 hour before kicking the return pump back on.
I keep an eye on the population and make sure I always see copepods in both the DT and the sump - so far, so good. The Mandarin eats all day and I still see the little buggers and it seems their numbers are increasing nicely.
The main thing to look for is population crashes where all of a sudden most of your copepods die off, at which point you'd want to replinish them, and figure out what might have caused the crash.