its 18x17x36....as in 18 deep, 17 tall and 36 long. the bulkheads are CENTERED at 2inch from the side and 3.5 inches from the top and I believe they are 1 or 1.25 inch. They already have necks on the tank side that you could turn enough to "set" your water height, or at least thats how I think that would work. as mentioned there are 2 of them on each side on the back.