I plan to remove the floor in the near future(when the wife ain’t lookin) so in the mean time I came up with this solution and hope it works.
Note: I always carry my plants outside to water them and then let them sit a couple hours and carry them back inside.
I took and cut the top rings off of 3 gallon plastic pots, drilled holes in them. They fit perfectly under 4 gallon cloth pots. I tested it by watering a plant and setting it in there on the ring and waited a while, checked the carpet underneath and it was dry. I just did 10 plants and will check the floor tonight and see
I used my oven grill, sitting on top of 4 little jars, on an oven tray for my first couple of grows, was only two pots.
I’d still lay down a cheap waterproof tarp though, even if the carpet doesn’t get wet, mold doesn’t need much to take off. When your plants get bigger you’ll likely get condensation inside the rings as humidity rises along with the size of the plants.