High Everyone, sorry it has taken me so long to share what I have done with the growroom floor. It seems that it will work very well. So the pond liner idea I thought was great. The only concern was that since I do soil and buckets, dragging the buckets on the Styrofoam would tear it up enough that water would be able to seep in again. Pond liners are tough and puncture resistant but, I still felt that safest thing for all was to cover the pond liner somehow. so what I ended up doing was after the pond liner was stapled to the wall ,I coved the pond liner with a piece of plastic lattice from Home Depo. The buckets slide around fine and if they do leak the water will end up in pond liner and I can take the shopvac and vacuum it up. For my 14x 10 rooms, the whole floor, was under $200 to complete. I'll keep you posted and let you know if it works or not.
Again, thanks everyone for all your ideas and taking the time to respond!