Photo update to check the HPS height. Temp at the top of the plants atm is 22-23 Celsius or 72-73 Fahrenheit. What troubles me is the humidity, it's constantly over 65-70% and yes there is an air exhaust fan in the room... Anyway I'll see what I will do with the humidity nvm that.

http://img3.imageshack.us/img3/1948/p1220243a.jpg

Should I foliar feed em with the growth nut + root booster or just the root booster? Should I reduce the quantities from what specified in the schedule and how much/often should I feed them?

Here's the nut schedule for your reference.

http://www.hydroponics.eu/img/schema_bio_en.jpg

Thanks again guys and sorry for all the questions...