I have a limited space of 18" wide x 18" deep x 36" tall (30" after HPS light). Is this going to be a big enough of a grow space? My 100 watt HPS has a metal shade w/ glass lens underneath the bulb. I will vent the box with a computer case fan. I also have (4) 2'-0" long fluors in the corners for vegging stage with mylar on the walls. How many plants can I grow and what kind of yield can I expect in this space. Just looking to grow enough for me.