help all the way :)

hi, ive just started growing after reading about it on these forums and others. ive smoked for years and havnt once thought of growing my own, i mean how dumb is that!!! anyways, ive bought a hydroponic nft system, but atm my babies are only sat in the rockwool under a 400 watt hps. my grow room is 3x3x7 in size. temps are 75-83c, humidity 50-60%, and ph is approx 6.0 at feeding. im using reverse osmosis water which reads 48 ppm on my tds metre (buying blue truncheon ec this week), after adding 1/4 strength nutrient (formulex) the water reads 161 ppm. ive read in places that i shud aim for 700 but atm im unsure how to go about reaching that number. theve been growing now for 7 days. yesterday i gave some superthrive to em and about 2 hours later they developed yellow veins and tips. ive eased of that now. anyway, im posting pics and keeping a journal in the hope someone might give me some advice along the way and in the process save these plants from certain death . thanks

peace

bb with pics soon