Depending on the size of your tanks, circulation and O2 levels you can grow redclaw in stacked or hung individual growth units which prevent other species from depredating on them. If seen this done with a variety of different mediums, including medium to large plastic bottles (Lifewater, Gatoraide, etc.)or my favorite, PVC pipe ( 3, 4 or 6 inch diameter) with a series of holes drilled in the pipe and encased in tube netting ( 1/8 or 1/4 inch mesh). The plastic bottles only need numerous holes of the right size drilled in them. With either method include 1/4 to 1/2 cup of pea gravel or your preferred medium in each container so that algae and bacteria growth freely occurs for the redclaw to feed on. You can work your own system out so that it works for you. Good Luck......Dale
PS - If your worried about any leachate from the bottles I would stick with the PVC which is chemically stable and used world wide in agriculture and the food industries.