Currently consider 2 IBCs, one for red claws and one for perch. Each would feed it's own hydroponic system.
Avoid bacterial/pest issues from mixing on one system.
Also gives me room to make one more suited to flood/drain trays, other running continuously as NFT.
Red claws don't like strong flow. Whereas it might be better for the fish one to have current.
A red claw supplier sent me this advice:
" You should be able to stock them for such a purpose – stocking rate - good rule of thumb for stocking density is for every 10 kgs of crayfish you have 1000 litres of water . Use netting in your ponds to give them habitat and to allow them to use the entire water column. Over stocked tanks and ponds will lead to poor growth rates irrespective of quality genetics and good water quality. obviously some form of aeration and a biological filter will be necessary in the stocking ponds as well. "
PS. 100g cray is edible, so I could stock 100 adults in the IBC (or a range of sizes is my intention, with 20 brooding stock).
Haven't determined number of perch per IBC ?