I ran my pump 15 min every 8 hours, after my plants got about 10" I increase my water cycles to every 6 hours.
I don't give them any water during lights out and I run my lights 18/6
I try to maintain a ph of 5.7-5.8 Don't go crazy with the nutes it's better to have less then more because with an ebb and flow system the problems will happen quickly. believe me I been there and don't go by what the back of the package states for using nutes, you need to only use 1/4 strength the first week and 50% the second. I'm into my 5th week of veg and I still don't use full strength nutes. Start off slow.
My plants are 11" right now and they're getting 750ppm and doing great. First 2 weeks I had a lot of problems and it was because of the ph and nutrients being to high. Air curculation is a big factor also as is the height of the light. To low and it will cause heat stress. I keep my light (400hps) almost 30" above my plants, any lower and I have problems with heat stress..

Hope this helps