I like hydro trays as frag tanks. Here is my ghetto/DIY/it aint pretty but it works approach. Different than exactly what you asked but maybe food for thought.
I use this tank
supported on this shelf (I add 5/8" plywood supports to each shelf holding a tank)
Steel Commercial Shelving Unit from Edsal features a rivet lock system that provides strength and rigidity. Easy to install.
www.homedepot.com
It grows lots of frags. I really like the wide shallow shape for this application.
Only challenge was the obvious one - huge surface area to volume ratio means high evaporation, which leads to heat loss. 9 months of the year, I keep it covered with a large sheet of thin plexiglass. In the summer, I leave the cover off and use that evaporation to my advantage to keep things cool.
Also important to ventilate the frag tank room well, because all that evaporated water turns into high humidity and can cause mold if not ventilated.