Quick Hydro Question about PPM

I am starting a Hydro grow. It is a a homemade Drip water system. I have a 20 gallon resivour with a large air pump (350 gallon capacity) and 2 air stones that run the distance of the resivour. I will transplanting my plants into the Hydroton clay pellets in a week or so. What PPM and Ph should I start with, considering I haven given them any nutes yet. Also, incase you were wondering. I'm going to grow 8 Low ryder 2. I chose them, because they were much easier for me being auto flowering, and short grow time and the fact they don't require as much room. I have some experiance growing Low ryders and also regular, non auto flowering strains in soil. I just havent grown Hydro before. Also, how long should I run the pump and how long should I let them go dry per day? Or do I run it all the time?
Let me know what you think. I'll be sure to thank good answers with some REP..

Umm, that was not a quick question.

If you're growing hydro, you need to feed your plants. Young plants can live on 400-500ppm, but they need something. Most drip systems into rocks run constantly. Keep your pH between 5.5 and 6.0.

HTH