If I remember correctly, you started with all dry rock, right?
Do you have a refugium going in the sump yet? A nice ball of Chaetomorpha algae is a great home to your pods, and they'll work their way through the rest of the system. Live rock rubble piles also make good pod breeding spots.
Have you seeded the tank with live pods? Several websites sell live pods, I'm sure some are more reliable than others. For a tank of your size, I'd probably do a couple adds of 10,000, introduced late at night when your fish are sleeping.
I might consider pulling the filter socks before adding the pods, then maybe putting them back in in the morning.
Mandarin's are so cool. I am still waiting for the day when I feel my tank will support one, eight months in and it's not there yet. At only 75g total system volume, I'm not sure it ever will be.