This system requires a liquid based fertilizer, as any particles will get stuck in the pump, sprayers, or drains. I also find that the powder based fertilizer collects on the bottom of the reseviour. I use General Hydroponics brand fertilizer for all my hydroponic systems. I also use a supplement, such as vitamin B-1 with micronutrients. You mix these together based on what and your progress on your grow. Here's how it works:

Thats all per gallon of pH balanced water. The pH is crucial to optimal growth. You should have a chemical based pH checking system to check your water after mixing the solution. I find that leaving the water uncovered overnite nuetralizes the pH a little bit. I have both the chemical based and electronic based pH checkers, but I had to calibrate the electronic one with the chemical pH set. General Hydropnoics sells these as a kit, containing pH Up and Down solutions, a dropper, a small test tube, and the pH checking solution.

To use the chemical pH solution checking method, fill the test tube up 1/2 way and drop in three drops of the pH checking solution. Put on the cap and shake it, comparing the color to the chart on the side of the pH checking solution. It should be Yellow/Green, or 6.5 pH. If not, use the pH Up or Down with the dropper to adjust the pH level, then check again using the method above.