Number of plants that can go in an ebb and flow system???

Hey guys i'm just wondering how many plants can be grown properly (not sea of green)in an ebb & flow system that is 18"W x 36"L x 7"D and one that is 24"W x 48"L x 7"D. The reason I'm asking is because I realy only want to grow about 5 or 6 plants tops, so if i can do that in the smaller system i'd rather buy that one and save a bit of money. I plan on growing indica mostly if that helps yu guys with my question at all. Hope some one can help me out so i can get started on my first grow.

Thanks

You will need a minimum of one square foot of tray space per plant. You should have room for three plants.

Thanks for the info. I guess i'm going to have to buy the 2 foot x 4 foot instead, Oh well it's only an extra $50.