Sorry I did not explain my situation better. This will be a perpetual system, with one tray going in 1 month after the other one. So the older tray with clones will be taller than the new one going in. I would like not having to tie all them down, as that would be a PITA. They will be under a 1000W HPS, SOG style in two 2'X3' trays. (The cement mixing trays from Lowes.)