On the primary tanks I used hardy board and steel stakes hammered into the ground to construct the shell. I think that for this bank of tanks I will try to use a more simple and cost effective material.
Let us review the situation. We have to protect the tanks from UV light infusion or else we will have algae buildup in the tanks and deterioration of the polyethylene tanks themselves. Next, the material that we use for this purpose must be able to withstand the damage that UV light can produce.
One of my neighbors, who is also installing rainwater IBC totes, found these covers: