Okay, so I'm letting you know, I have no experience with pacs, but a lot of info from the great people on this site.

They don't like to be picked up, it stresses them, and this is probably why, he is doing what he's doing.

IMO, if you've been keeeping the proper care of the tank, water, and feeding routine, I don't think it has anything to do with the tank.

Someone on here is going to respond (probably BG) who knows pacs like the backs of their hand, they'll help you out!

All the best,

~Royce