I made this exact system for my first grow, although I used a larger tub that was able to hold 6 plants. A couple things to watch out for, the tub will begin to bow the more water you add, especially if you have to drag the tub to and from a water source. For this reason I would reccomend adding some type of valve at the bottom of the container so that you can easily hook up a pump and pump the water in and out. If you do this make sure you seal the valve really well because you dont want it to start leaking one day when you arent there. Another problem I ran into is that the plants grew so fast some quickly outgrew there allotted space while other were slower to grow. I would reccomend only three or 4 plants. For and 18 gal tub I use two plants, however if growth is controlled and flowering is induced early you could opt for a more sog method. Good luck with your grow. -Diz:rasta: