its about deminishing returns. <50wpsf and the growth will be slow. >50wpsf and the increase in growth is not inkeeping with the increse in power used. in real world turms for a hobby grower it dont really make any odds as small lights like a 250 costs only pence to run but when u start to use multi light setups pullin a coupple of kw's u want to get asmuch return for ur investment as possable be it as a busness or to keep the lecky bill down. i never said u wudnt get lusher growth with 100wpsf over 50wpsf cus u will, but u wont get twice the yeald. u will get twice the heat and it will cost twice as much to run tho. using the light well, keeping it close to the plant etc is the most important thing. a 1000w light bolted to the top of a dark walled 6foot closet wont give as good results as a 250w just inches away and surounded by mylar. even tho u have 4x the watts its wasted. the point being u dont need big lights in a small grow and there r no hard fast rules when it comes to growing a living thing. any1 can give perticular examples to prove any point as ther is allways an exception to any rule and other factors that may not have been taken into account. i once argued while pissed in a pub that black was white and white was black, went outside and got run over on a zebra crossing (j/k) the whole reasoning behind the post u quoted was that u dont need big lights and they can b more hassle than there worth. any1 can grow weed, but if u wanna do it well then its a balanceing game of light, space, heat, nutes etc and the less u put in compared to the amount u get out defines how well ur doing, doesnt it?
hey thug, you're right. twice the watts is not twice the bud. us small timers have to get any little extra we can! besides 100w aint shit. I use that every time the kitchen light comes on. hippytoke, just experiment & pack in as much light as you can cool/afford. just got my closet together. gonna be pushin 9800 lumens per sq ft. some say its overkill, others say put some floro's in the bottom to get even more bud. Have Fun, Dirt