Either is fine, depends on what's cured better. Dinos are hardier overall but will roll if weak or uncured. The square shape is the problem as the other fellow mentioned--round or oval is the best. Also, bait will die from it's own urine, etc. if it's just an aerator not a continuous fresh supply bait tank. He's right-on too about not crowding the tank. Your water should be completely renewing every 6-7 minutes ( if I remember correctly). Go to http://nexmar.com/tech_info.htm for additional info.