I have not had that prob. with the pellets, but I did stop using them after a week. I lost 5 of my basque chicks in 3 days. They were squishing each other to death! I couldn't figure it out, DH is the one who pointed out to me how hard & stiff the pellets are so that when they all pile up the ones of the bottom were getting smashed to death. I loved that the pellets were so much cleaner and the poop smell was gone- but it also cost me the chicks. Since I changed back to shavings I have not lost any more chicks.
That sounds like they are too cold under the ecoglow. I use an ecoglow 50 and they never pile on top of eachother for any reason :\. I do not use loose bedding until they are around a week old. I start them off on potty pads for dogs.