A couple of solutions to help with evening out water flow:
1. Design your water supply as a "tee", with the hose attachment coming from the center rear. I hesitate to call it a "spray bar", as it should really sort of be a slow, steady flow, with no real force coming out. Like water coming out of a water fountain.
2. Do not position the holes pointing down; rather point them so the water comes out the top of the tube, and drain down around the outside of the pipe...or point them toward the back of the table.
3 Have a porous pad below the water streams coming in, (upstream from your dam) that will easily saturate, and the water will flow through it easily, and will "ooze" out and spread across the table evenly. Cloth or sponge DON'T work as well -they will just saturate, and the water will flow over them. 3M Scotchbrite pad, or a piece of cut-to-fit air conditioner filter (looks like tangled hair) matting, about 2"-3" wide across the width of the table works well. The pad can be charged with JetDri or whatever surficant you choose to cut down on bubbles and floaties.
