Lynn,
one more thought, like are hot tubs up north here, put the tanks on 2" dense pink foam insulation, I do not know there shapes, are these Rubbermaid stock tanks? Insulate the sides, wrap fiberglass imsulation around them, use 2" dense foam isulation for covers, and 2 chillers to cool them. The down side, the cost of the chillers, and they will not be real effient useing that hot garage air to cool their freon. But if the chillers could be in the house, and piped to the tanks would be better, but then the house AC has to cool the heat from the chillers. There is nothing in this world that puts cold into the atmosphere just heat, an earth week tip of trivia. I have a Bacholar's in ME. My mentor in this hobby is an Electrical Eng, never read instructions, screws up more stuff and I have to bail him out, like his Vortech PH, $800.00 broke, he never read all of the mounting instructions with the pin placement.