Crysmatic
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You said a 250w can yield 67% more than a 150w....but based on you and squiggly plants don't respond to watts. If you go back to the 1st page of this thread I said "I think its possible if you veg longer when reducing watts in flower but if its the same veg time, strain, and all other factors the exact same I don't see how less watts gives you more yield."
Now that was an answer to the title of this thread. Thats basically the point I was trying to make this whole time because a couple people said "plants don't respond to watts and we should be talking about intensity." Now you basically said the higher wattage light produces more bud which in turn obviously means its more "intense". That is what I've been saying during this entire thread but you and squiggly kept dissagreeing with me then changing the subject and talking about scientific photons and shit. You said it with your own words, the higher watts, the more buds. Thanx
ALL OTHER THINGS BEING EQUAL. Lumen conversion being one of those things! A 400W HPS was the standard for 1+ gpw. You can't compare HPS, MH, LED or fluorescents on a Watt basis - or even HPS with different lumen conversions. However, you CAN compare lumens at the canopy for ANY light (understand that I'm still making a general statement, and that reflector efficiency and spread affect yield) (damned caveats). I believe yield comes down to total lumens during the flowering stage, regardless of spectrum (disregard black lights, or incandescent bulbs). Lumens is the #1 priority! The rule of thumb (not a LAW) is to use the highest wattage bulb that you can fit in your space (HPS is king).
I was trying to give a simple comparison - you're really just splitting hairs and arguing in circles. If you want to get specific, an eye 400W HPS has 52,000 mean lumens (130 lumens/W), an eye 250W HPS has 27,000 mean lumens (108 lumens/W), and a generic 150W HPS has 13,800 mean lumens (92 lumens/W). The higher the lumen conversion, the more bud per electricity used. i.e., if the 400W HPS yields 400 g of dried bud, the 250 W HPS would yield 208 g, and the 150W would yield 106 g. From an initial cost analysis, if you paid $150 more for the 400W vs the 150W, how much would you save in pot in just the first crop? The 400W would yield more per dollar spent than a 250w, and especially the 150w.
We're only talking about yield vs nominal lamp output. What about electrical consumption? A 150W HPS uses 200W nominal (33% waste heat). A 250W nominally uses 300W (20% waste heat). A 1000W HPS magnetic ballast uses 1097W (9.7%), and a digital 1000W ballasts use about 1065W (6.5%). A 600w HPS is the most efficient bulb to use, as far as lumen conversion, and electrical consumption.
I've read a greenhouse study where fixed lights were better moving lights - plant mass is directly related to average lumens multiplied by hours of light. The intermittent high/low light level from light movers averages fewer lumens than a fixed light. Basically, if you use a light mover to cover 32 sq.ft, you'll still yield the same as a fixed lamp over 16 sq.ft. Light movers offer an advantage over poor reflectors as far as shadowing and even light distribution. Multiple, smaller lamps, in place of a single large do offer less shadowing, and more even coverage - assuming the reflectors have equally even coverage. Four 250w may have more even coverage than a 1000W, and has lower total lumens, much lower yield, less penetration (need really short plants), much higher electrical usage, and much higher bulb replacement cost - it's absurd to suggest using 250s.
I still recommend forgetting about "experimenting", and just learn to grow bud the best you can. Real researchers DESTROY their crops after a trial :oops:
thanks lex for making me think. i actually learned a lot. I hope I've communicated it well.