pods for my goby

I recently got my daughter a mandarin goby, and knowing that they feed exclusively on pods i set up a few rubble piles in my DT and emptied a bottle of tiggers into them (as best as i felt i could anyways). The problem now is that u dont really see any running around in the piles, and i feel i should since two of them are in the front two cornees of the tank.



So i guess what im inquiring about is how to effectively create a self propagating pod population in the tank. My piles are maybe a bit small, about the size of a softballeach, maybe a bit bigger, but are butted up against areas with lots of other hiding spots. Do i need bigger piles, or is there some way to get the little buggers to initially go into the piles or am i thinking about this all wrong. I dont have and wont have a refugium for a couple months still, so what to do.



Oh, i do have a small native population of little white pods, so i know i can support them, i was just surprised that it seemed as though nobody survived the initial seeding attempt.



Thanks in advance for the tips.



Rich.