some white things on my glass
Unfortunately reefers have used the words pods
to describe both amphipods and copepods. You likely saw an amphipod scurry away. The little white thingys on your glass are most likely copepods.
I was happy with the last 2 good orders from IPSF.com and my local reefers group is taking a field trip to Inland for the January meeting.
If you don't have a lot of coralline, you can buy a piece of LR
with a lot of it. It will eventually spread. However, if your tank chemistry is stable you can also scrape coralline off of it in front of a powerhead to get the spores spread around the tank.
I would not add a mandarin to a 30 gallon. Mandarins are pod eating machines and almost all of them will not switch over to prepared foods.