A bit in trouble here choosing the lamp wattage and exhaust/fan and lamp choosing. So my space width:25", height:45", and depth:23". I will have two short strains, up to 60 or 70cm, or maybe even less, how strong hps lamp will be better, 250w or 400w,maybe 150w? Maybe later i will want to grow something more bigger, is it possible? Thanks a lot guys.