I need some plans so I can frame a 12"x4'x16' Plywood float trough grow bed in a way it will hold the water weigh. any help for this will do. I will line it with bed sheets coated in rubberized non-toxic roof coating I can build it up to 6-8mil thick or more that way. It will be flexible and virtually puncture proof. But the frame need to be tight with very little movement once the water is put in.

things like how to tie 2X4 together to hold the plywood tanks, also placing it off ground with 4X4's on blocks. We have really wicked termites here and even though we will treat the ground and the wood I don't want to give them any hiding place under the float trough grow bed.