I have been growing indoors for quite some time now, and would not consider myself a beginer, but I did have a thought on saving electricity and possibly maintaining yeild. I am planning a closet garden for a friend who wants to keep energy usage at a minimum. Has anyone ever tried switching between 250w-400w hps during flowering? I was considering a setup that would allow monthly harvests. After veg, clones would be placed for two weeks under 12/12 250w. Then for weeks 2-6 of flowering moved to 12/12 400w. Then moved back to the 250w 12/12 for the final 2 weeks of flowering. Once started this leaves a perfect cycle where both lights are always being used (no down time ideally). The reason I am hypothesizing this might work is that most of the yield weight is gained in weeks 2-6 (mainly 4-6), and this is when the plants will be under the more intense 400w light. During the first and final weeks the plants seem to be going through processes that depend less on light intensity such as the stretching period before buds begin forming, or the last week to two weeks when growth stops and you are just waiting for the bud to ripen; It seems like a 250w should be plenty bright enough for this. I just thought of this and have not tried it, but was wondering if anyone has tried it, or if anyone has any thoughts as to why it would or would not work.

If you really want to conserve cfl's are the way to go. I haven't seen anything that suggests a significant difference in yield using them if it's setup properly.

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...flowering.

My goal is to yield as close as possible with a 250 and 400 as would be possible with two 400s by giving the intense light when it is most needed.

Don't underestimate the actual growth that occurs those last two weeks.. Aside from that I agree with you, mainly because if 400W is sufficient for the area of the fulfilled canopy, then packing them a bit closer together earlier under a 250W, you could get the same irradience..
To keep the convenience, early vegging works great with cheap cfl's.. Aside from that though, they're for ppl who don't really have proper setups IMO.. Not that I'm knocking ppl who pull them through because they have no better option for their growspace.. A light smoker can sustain themselves with a few cheap cfl's..

Try an HID on your own and you sure will. I sure as fuck miss mine.

Don't be fooled. 8000 Lumens < 35,000 Lumens

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Loose lips sink ships.

Perhaps you can try DutchMaster Liquid Light during your 250w flowering weeks??? Great question...keep me posted, I'm interested in seeing how this turns out.
+rep

I agree cfl are useful for vegging, and that is what i will most likely use, but for bloom they just don't compare to HID. I usually yield approx. 10-12 ounces from a 400w flowering 60 days. If I can stay in that range (10-12 oz.) and use 81% of the energy by using a weaker light at opportune times. The savings on a setup this small would be noticeable, but not huge. If this works, however, it could be applied to a larger scale grow and make a large difference when you consider not only the initial savings on light wattage but also the reduced heat. Honestly, I can't believe no one has tried this. I can't be the first person to think of this. I guess I'll have to be the guinea pig.

I really think you'll regret dimming the lights late flower, I really think you'd be better off reducing day length if you're dead set on trying something.. But even then, 400Watters don't shine that intensely, so I really think most plants can effectively use that intensity for the full 12 hours.. I have an interesting pdf on chemical reactions involved in photosynthesis that explains the ups/downs of super intensity pretty clearly without need for any background in chemistry, but if you do know your chem, it covers alot of interesting stuff.. PM me with an email that can accept a 1.2MB pdf if you want it..
Gotta remember your 400W is giving you 12oz in 60 days.. Around here, at $200 an ounce thats $2400/720hours.. At roughly 10cents/kwh thats like $2400 for less than $40 investment over 60 days.. There is no power usage threat AT ALL from your setup, you could use 5x that much and not set off any flags if thats your concern, but aside from that, even at the cheap weed value here in Ontario, thats $60 equivalent in product for every dollar invested..
Whoa, the dutch have taken wave particle duality to a whole new level.. I never knew that product existed.. Now I have even less respect forthat particular company.. (Not that I've tried anything by them)..
Wilson was too tactful IMO.. Thats the dumbest thing I've heard this week..

8000 lumens 2x closer is 2*2 times as bright.

So, 4*8000 = 32,000 < 35,000.

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Why people believe strange things: http://www.youtube.com/watch?v=8T_jw...eature=channel

Well, that reasoning sure tips the world of growing on its side huh??