Planned Layout of the Greenhouse

I have been working hard for the last six weeks at figuring out a layout for my greenhouse.  I have gone through a number of iterations, figured out the obvious flaws to my plan and then processed the revision.  This is a scan of the iteration that I am currently going with.

The layout in the center is the floor-plan of my 12x16 foot greenhouse.  I started with a plan that had a door from the greenhouse going outside, but I jettisoned that plan when I realized how much area that eliminated from my plan.  Now, the only way in and out will be through the existing building, which is ok.  I am planning on partially burying two 250 gallon fish tanks on either side of the door.  The door as drawn is not in the right spot, as you can tell from the photos it is centered more.  The green rectangles are 2x4 grow beds, and there are ten of them.  There are two black grow beds of the same dimension of which I plan to use soil to experiment with some different types of root vegetables that seem to grow to a better shape in soil. 

On the sides of the center layout, I have drawn an elevation of each side of the greenhouse.  I am planning to build a two foot high stand to place the grow beds.  Under this stand will be the fish tanks and the biofilters and sump tanks, which are colored in red.  At the end of the center section of grow beds, I will be building a structure to place a couple of smaller aquarium tanks.

I am sure that there will be several things that I will figure out as I go that will cause me to tweak this layout.  My plan is to construct everything in a way where I can change the layout without any serious problems.  This is why I am not pouring a cement slab on the floor, in case I want to change the layout and bury any plumbing or tanks.