Lissa - Marc's issue would be the 'vertical' measurement of 30 inches possibly sagging. The 72" length isn't an issue as the frame for the netting would sit on top of the edge of the tank. I'm with you that we need top down shots!!
Marc - if the edge of the tank is 3 inches, then we're only left with 24" to span..correct?
I'm heading out to my plexi place today and will grab a small piece of 3/8 and prop it up under my lights to see how much abuse it takes. Will assume all of your bulbs are 400w. Also curious to see how much light gets past the 3/8 thickness.
I still like the 3 panels for ease of movement.