Zandor, thanx man for the info&advice.....what i plan to do is not to use the entire room space....i could not possibly do such a thing without any proper ventilation......80 sqft is the entire space but in no way i am going to fill that space with plants.....with the window open at all times the cops would pay me a visit during the vegetation stage....for this grow i will isolate 12sqft of space with reflective material on a curtain....more or less this is the exact size of the NFT system with the tank and the tray.....this is going to be my grow space....with 800watts during flowering i will have a ratio of 66,6666667 (lol)watts/sqft...optimal i guess....and the good thing is that these 800 watts come from 2x400 HPS systems, which means that one will be from above while the other can be positined anywhere side/bottom etc.....as for the sativas, i know they get tall, but, can the rockwool cube support such height and subsequently weight? i do not have a problem with headroom....max ~ 12ft.
Finally, no co2 enrichment for the grow room will be used....the window will be open at all times providing fresh air to the plants that will be circulated with the use of fans....
gotta go now....take care people...time for a good joint with pure bud from grow#1...hehehe
NGOS