I have a built in ebb + flow system running, that i made a custom tray outa 3/4 ply with a pond liner which is some really rigid stuff, very inexpensive and easy to clean and fix if you do get an unfortunite hole" drop your drill while putting up your screen" been there done that. some pics of it in my grow journal. As for contamination from plastics or rubbermaid i would not worry about as long as the items are disinfected well with alcohol and rinsed well before use, but that goes for most anything. using wood might be a bigger concern if it is getting wet and not able to dry out, that can definitely cause some mold issues. I used 3/4 ply that i sealed with polyurethane before i covered it with the liner and used plastic sym board everywhere else. good luck and happy growin