I am in the process of transferring my livestock from my 14 gallon biocube to my 45 gallon cube and I was trying to move my BTAs over today, but I can't get them the move or let go of the rock. I tried the ice cube in a bag and still trying to annoy them with the powerhead, but it seems to going no ware. The rocks can't be removed from the tank. Any ideas on what I could do to encourage them to move?