Increasing nerds
I'm at 15 nerds every 2 hours. You probably have to update the castle a few more times. My castle is at level 9, so I think it went up to 15 nerds sometime earlier.
Forum Discussion
I think you have to keep upgrading all 3 castles to increase maximum number of nerds available. I have been upgrading all of mine and I am at a maximum of 55 nerds.
