A tank will only have as many pods as there is food for them to eat. If the food source decreases they will decrease. And as you found out, mandarins love to eat pods so that is another way to decrease the population. If you don't already have a refugium set up, I would recommend you doing so and putting some live rock and macro algae in it. This will help increase the population and add food for them. The quickest way to get more pods is to find someone with an established fuge that is looking to reduce their macro algae. Usually if you can get some macro from a fuge it will be loaded with pods. As you are in Cedar Park, try asking Tim Marvin. He usually has a good supply.