can you give more details on what table your using and where you got it, is the wall only 7 inches tall? is that enough to have an actual shallow lagoon like tank.
That’s a hydroponic table, there are many brands/sizes, and you don’t want to run them right at the rim.. for the standard trays, the bottoms are corrugated, so you should expect a 4.5”-5” water height across the high points of the tray bottom…
There are also shallow trays, but they are all but useless for this application.. however, hydroponic reservoirs, which are closer to 12” deep, would be a good place to look!
Either option would require a lumber frame for rigidity, but can be built into a table frame, and would be mobile if castors are added!
— another option are 50G Rubbermaid stock tanks, right around 9ft2 of bottom surface area, and 12” of water… also mobile if a wheeled platform is built, and no structural framing required!
— I’ll add that Reinforced PolyEthylene RPE pond liner material is some incredible stuff, compared to typical vinyl rubber liners! (24mil thick w/6mil thick UV protective coating is effectively impossible to tear by hand, even after putting a slice in it!)