Switching Lights to Save electricity?

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.

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..

Mystik said:

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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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

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..

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.

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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)..

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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Wilson was too tactful IMO.. Thats the dumbest thing I've heard this week..

wilsoncr17 said:

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

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

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

TeaTreeOil said:

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

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

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I don't think you are, but that sounds like 2x65w cfls at 4200 a piece could legitimately compete with a 400w mh? But that doesn't take the smaller footprint with CFLs into account at all, does it?

MH pumps out more 'photons'/watt than cfl (hps more photons/watt than MH), and you have 6x as many MH watts, then how do those cfls surpass the MH?

closetengineer said:

I don't think you are, but that sounds like 2x65w cfls at 4200 a piece could legitimately compete with a 400w mh? But that doesn't take the smaller footprint with CFLs into account at all, does it?

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You'd half to provide proper coverage of the 'hemisphere' of the plant. But yes, you could easily exceed a 400w HID by doing so, and also be using more wattage.

You still have to deal with properly reflecting the light though. Which is not such a big problem with LED's, as they are highly directional(most light is going in one direction, or a very limited range) light sources. It's not anywhere near omnidirectional. Like HID, CFLs, or incandescents.

born2killspam said:

MH pumps out more 'photons'/watt than cfl (hps more photons/watt than MH), and you have 6x as many MH watts, then how do those cfls surpass the MH?

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Actually. That's not always true. Some fluoro bulbs surpass MH efficiency (especially the lower wattage HID bulbs, like 250 and below).

While CFLs are most efficent at lower wattages(13 to about 42 actual watts). HID is most efficient at very high wattages(600-1000W).

And after a year, an HID is down to about 70-80% of the original output. CFLs tend to still be doing above 80% after 1 year with grow-light use(long period on, long period off). One major source of wear on CFL is turning them off and on a lot. They should be allowed a cool-down period of around 5 minutes before turning them back on to avoid this. Anyway, every time you turn them on regardless, like any bulb, there is wear.

LEDs do not really suffer in this regard. But there is still a very minor amount lumen wear. Mostly due to operating them out of specification.

fuck CFL's.........

I agree with most of that TeaTree, but I'd like to see data on any fluorescent that actually pumps out more photons (especially photosynthetically active photons) than any HID bigger than perhaps those cyclists use.. BTW, LED efficiency goes down as wattage goes up.. I recently saw my first half-ass impressive LED grow (the funniest part was the pink light.. If I ever grow with those I'm decorating the grow room in a My Little Pony theme because the room I saw looked like a 7 year old girl chose the light.. ) I'll concern myself more with LED when the technology actually makes them the right choice for anybody who can handle HID in their space..
I'm constantly bashing 'lumens' on this site.. Lumens are for humans, humans and plants don't have similar action spectrums at all! The only time lumens provide accurate measurement for plants is when comparing lights with identical color compositions, but different wattages.. Really we should be talking about µEinsteins rated against the plant's action spectrum.. An Einstein is a mole of photons (For those who don't know, a mole is 6.02*10^23 of something, exactly like how a dozen is 12 of something.. Seems odd I know, but it makes sense in chemistry etc because 1 mole of protons weighs 1g)..

All fluoros emit more PAR per lumen than any HID. Anyways, HO T5's can pump out over 100 LM/w. Which puts MH to shame(especially because T5's also last longer!). Google it?

LEDs do not have to be high wattage, they are extremely directional light sources(like flash lights), heck, you don't even need reflectors, really.

I've seen impressive plants grown under HID, fluoros(tubes and CFLs), and LEDs. Even under the sun, if you'd believe that.

LEDs are rapidly advancing, they have already surpassed fluorescent efficiency, and also LEDs exist in laboratories that surpass HPS in PAR and lumen output. The problem is keeping them cool and operational, while still affordable.... This could be a decade away, but I feel confident they're the future of lighting...(foreseeable) for all purposes. Until something better comes along, anyway.

Maybe you've seen this? 300 LM/w LEDs(beats HPS by over 2x): http://www.ecogeek.org/content/view/1415/

All fluoros emit more PAR per lumen than any HID. Anyways, HO T5's can pump out over 100 LM/w.

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Ok, if you want to toss an extra useless unit in there..
PAR/lumen * lumens/Watt = PAR*lumens/Watt, which is nonsensically contradictory.. Its kind of like saying you can fit 100 apples and 100 oranges in a basket, but not just 100 apples or 100 oranges..

I'm not following your dissection of my statements. I'm referring to the ratio, yes. PAR/lumen, calculating this for the bulbs... the fluoro would have a higher number... meaning it's more efficient at producing PAR than solely lumens.

Lumens per watt or LM/W is called the luminous efficacy.

Also, your math is wrong, lumen(s) would cancel, leaving you PAR/W. Perhaps that is why it doesn't make sense to you? But that's essentially what I'm saying, flouros can produce more PAR per watt than MH.

That sounds better, perhaps I misunderstood you.. Watts are energy.. Dumbed down, Watts can be turned into PAR, lumens, and heat.. More PAR/lumen translates to less lumens/Watt, more PAR/Watt translates to fewer lumens/Watt.. More heat/Watt translates to less PAR & lumens/Watt.. Its that damned 1st law of thermodynamics.. Here is the kicker though.. HID produces less heat/Watt than anything else at the source.. Thing is, heat can also be produced by photon fluorescence away from the source, and the more PAR or high lumen photons the source provides, the greater that will be, as is the case with HID.. Fluorescents (which could be referred to as LIDs I suppose) actually produce high energy UV photons that 'fluoresce' to visible when they interact with the phosphor coating unless they keep getting reflouresced to heat before escaping.. (One advantage they have working for them is the thin envelope means less subsequent flourescence, and more effectlive heat dissipation..) Its a pretty general rule of thumb that every stage of any process adds (or more correctly multiplies) its own inefficiency to the total.. HID (especially HPS)fluoresces visible to heat at every obstacle, and its so noticeable because of the immense low energy yet visible photon counts.. Actually fluorescents do too, but its less noticable because of lower numbers of photons/unit area.. Beyond that, not all photons cost the same amount of energy.. If you're familiar with E=hv then you'll notice that 1W of reddish light carries signifigantly more photons than 1W of blue or UV light.. Its PAR photon counts that plants really care about, photon counts are measured in µEinsteins (an Einstein is a mole of photons)..
If you come across any data regarding visible/PAR photon counts on any fluorescent then please post that.. I never really found anything of the sort for anything really modern, but I remember my optics text that was written in the early/mid-90's I believe charted some numbers for various general light types, and HPS/LPS dwarfed everything else with MH beating fluorescents by quite a bit as well..
I'll see if I can find that book and post what it has, even if it was basing on older, not clearly defined technolgy..