the things i have noticed is that if they have 24/7 food,water and cleanliness you dont get any chewers.. maybe there is something that you are doing that is causing them to want to chew out. maybe temps play a roll? too hot or too cold. ive been using teh same tubs for over a year and i dont have as much as a single chew mark in any of them. maybe i got lucky, but im betting that you are missing something that they need.
adam jeffery
btw my setup is home depot tubs, automatic watering, i clean every 3 to 4 days. always have hoppers full of food.