building a system 8x4 feet

[animus_divinus]

hey everyone.. im building a hydroponics system in less than a month... its going to be 8x4 feet in size, 32 square feet, about 10-11 cubic feet in total

im buying a 600w ballast kit for $100, plus a 600w bulb.. ill make the reflector myself to cover the entire table

well, id like to go with an ebb and flow system.. put a 1/2 inch PVC pipe through the bottom of the tarp-lined table, glued in to make a seal.. 8 of them, each one supplying a 4 square foot area and linked together 4+4 and then a 2 into 1... nutrients will be pumped through all of these drains and then released in a typical ebb and flow setup

what i need help determining is the grow medium... i have to fill a 96x48x4" area with grow medium for this system to work as planned, or plan a new one... frankly, this seems the least expensive route having all plants grow side by side on a table filled with the medium...

if anyone has any better ideas to set up an ebb and flow system of this size, id love to hear it

however.. gravel and sand is heavy... i think for sand or pea gravel im looking at the table holding 1,000lbs in medium alone

if i use perlite, then i have the issue of the stuff floating, though i could stretch a mesh screen over it and staple it down... the loose leaf lettuce would probably find its way through holes in the mesh? and holes could be cut to make room for the stem of other plants

ive thought about using tubes with holes cut out to fit a styrofoam plug holding the plants inside a pipe which can be flooded and released like a typical ebb and flow system.. but it would be too difficult to get this to work on smaller plants too

basically, im looking to go as simple as i can while being able to accomodate larger plants, and small herb/spice plants too

any suggestions will be helpful