ive just bought a grow tent just thought it was the easyest way to start of,ive got a 600 watt dual spec bulb for only 2 white widows and 2 great white sharks,how impotant is it to have freash air entering the tent at the bottom,the tent is 100cm square and 200cm high,plus how high should i have the light cus it gives of alot of heat and i dont want to burn the plants,i also have a high powered extracter coming from the top.thx 4 your viewing.