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Offlinepheed
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using MH light for seedlings?
    #500212 - 11/23/10 12:29 AM (6 years, 13 days ago)

I've read that during veg, a 250W MH light can be about ten inches from the tops of the plants, but that for seedlings, MH lights shouldn't be used at all unless they are kept 3-4 feet away. Won't this cause stretching?

My Lumatek digital ballast will let me dim the light to 100, 150, or 175 watts. Could I just dim the light for seedlings without having to move the light so far away?

I should mention my light is in a cool tube...


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OfflineTheShroomJew23
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Re: using MH light for seedlings? [Re: pheed]
    #500213 - 11/23/10 12:59 AM (6 years, 13 days ago)

The reason fluorescents cause stretching is because their light intensity drops off extremely quickly within a few inches away from the light source. Whereas MH and HPS have very strong intensities. We keep the lights so far away during seedling and into vegetative because they simply can't handle the intensity so they die.


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OfflineGoombah
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Re: using MH light for seedlings? [Re: TheShroomJew23]
    #500303 - 11/23/10 01:41 PM (6 years, 13 days ago)

I used 1000w MH on my seedlings (about 8 days old) at about 4' away. The plants didn't suffer at all. No stretching whatsoever.


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OfflineTheShroomJew23
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Re: using MH light for seedlings? [Re: Goombah]
    #500310 - 11/23/10 02:21 PM (6 years, 13 days ago)

Thanks for the backup Goombah


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InvisibleMagashM
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Re: using MH light for seedlings? [Re: TheShroomJew23]
    #500312 - 11/23/10 02:59 PM (6 years, 13 days ago)

Fuck this drives me out of my fucking mind. Ok, that wasn't meant to be aimed at you but I have no idea where the fuck this seedlings can't handle strong light shit came from. They start in the sun out in the wild. Even mild sun is way brighter then any hid light.

I've started so many seedlings under 1000 watt lights raised up to the tops of the other plants I can't even begin to count.

These are Nirvana AK-48 started under 1000watt MH and still doing just fine under it.



The only real way to fuck up seedlings under hid's is to put them to close and cook them.


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InvisibleInverted
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Re: using MH light for seedlings? [Re: Magash]
    #500340 - 11/23/10 04:32 PM (6 years, 13 days ago)

Quote:

Magash said:
They start in the sun out in the wild. Even mild sun is way brighter then any hid light.

The only real way to fuck up seedlings under hid's is to put them to close and cook them.






:bigyesnod:


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Invisiblemaryanne3087
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Re: using MH light for seedlings? [Re: Magash]
    #500429 - 11/23/10 10:40 PM (6 years, 12 days ago)

Quote:

Magash said:
Fuck this drives me out of my fucking mind. Ok, that wasn't meant to be aimed at you but I have no idea where the fuck this seedlings can't handle strong light shit came from. They start in the sun out in the wild. Even mild sun is way brighter then any hid light.





I grow my seedlings under HID also. The sun is not brighter than any HID, it's actually very easy to provide more light concentration than the sun even on the clearest days at high noon even with cfls.

Have you ever seen any leaf bleaching on any cannabis plants outdoors? Probably not. Have you ever seen leaf bleaching on cannabis plants indoors? Probably if you run a lot of watts/m2.

A 600w over a 3x3' canopy has stronger light intensity than the sun (barely), I believe a 600w over a 3x3' canopy is supposed to match the strongest sun light exposure possible in nature. Then considering that the sun is only brightest once a day and there's clouds to block it frequently growers can and usually do provide much more light throughout the day then their plants would get outdoors. Weather or not it's a bit less or a bit more, a grower can choose to provide far more than 600w over a 3x3' canopy if he or she so wishes, which would far exceed the sun's capability.

I believe that a typical meter squared gets 1kw at high noon during summer at the upper atmosphere but much is absorbed by dust, ozone, water vapor, etc and about half of that reaches the ground.


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Invisiblemaryanne3087
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Re: using MH light for seedlings? [Re: TheShroomJew23]
    #500439 - 11/23/10 10:58 PM (6 years, 12 days ago)

Quote:

TheShroomJew23 said:
The reason fluorescents cause stretching is because their light intensity drops off extremely quickly within a few inches away from the light source. Whereas MH and HPS have very strong intensities. We keep the lights so far away during seedling and into vegetative because they simply can't handle the intensity so they die.




This would only be applicable for florescent lights that are far away from plants.

Stretching has a lot to do with color spectrum

ie. red to far red ratio influencing phytochrome response
ie. blue spectrum influencing crytochrome response which controls elongation and photoperiodism

Phototropin also responds to blue light and are responsible for elongation and environmental response, they're also active before the crytochrome and control the first elongation of the plant (controls your seedlings being stout or stretchy skinny bitches)


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InvisibleMagashM
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Re: using MH light for seedlings? [Re: maryanne3087]
    #500487 - 11/24/10 03:38 AM (6 years, 12 days ago)

Quote:

A 600w over a 3x3' canopy has stronger light intensity than the sun (barely), I believe a 600w over a 3x3' canopy is supposed to match the strongest sun light exposure possible in nature.


  Yeah maybe if the light meter is pressed up against the bulb otherwise your reading crap from books again but take the meter outside and tell me this cause I can tell you for a fact that a reading from a 1000watt HPS at 2 feet isn't as bright as outdoor light at noon. Not in California anyway. You must be taking readings from the top of Mount Kilimanjaro.



Quote:

concentration than the sun even on the clearest days at high noon even with cfls.


Not a chance in hell. Maybe high noon in Alaska during the winter.


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Invisiblemaryanne3087
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Re: using MH light for seedlings? [Re: Magash]
    #500492 - 11/24/10 04:06 AM (6 years, 12 days ago)

Yes, I do prefer to get my information from books rather than cereal boxes. I'm sorry you have a problem with this.

http://en.wikipedia.org/wiki/Solar_variation

Solar irradiance measures 1366 w/sq m the max is also 1413 w/sq m apparently and I'm fairly sure California isn't an exception nor is it the brightest place on earth. This is already beatable but would be rather extreme.  HOWEVER this is without any ozone, clouds, dust, etc to absorb any of it. After losing more than half of this to all that crap you're left well less than half :crazy2: leaving you with often less than what a 600w will provide over a 3x3' canopy.

A trusted cultivator on here says something more or less exactly the same as wiki and a million other websites. Who knows though maybe none of them had access to a light meter? :wink:

http://www.growery.org/forums/showflat.php/Number/282827#282827


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Offlinepheed
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Re: using MH light for seedlings? [Re: maryanne3087]
    #500493 - 11/24/10 04:44 AM (6 years, 12 days ago)

Thanks for all the replies. Interesting discussion...

My tent is just 55 inches tall, so the maximum I can probably keep the light is 3' from the seedlings. I'll probably try 2.5 feet with the metal halide dimmed to 150W for the first few days. Unless anyone has any objections??


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Invisiblemaryanne3087
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Re: using MH light for seedlings? [Re: pheed]
    #500494 - 11/24/10 04:54 AM (6 years, 12 days ago)

Dimming it should work fine. I used my 600w's at full blast at around 3' or maybe a less. I used a bare bulb though because I was scared of a hot spot at that point and didn't need crazy light intensity.


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InvisibleMagashM
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Re: using MH light for seedlings? [Re: maryanne3087] * 1
    #500567 - 11/24/10 02:45 PM (6 years, 12 days ago)

Quote:

Yes, I do prefer to get my information from books rather than cereal boxes




No the difference between us is I actually grow and do this stuff rather then quote stuff without ever trying it. I'm sure by your answer you don't even own a light meter why don't you try going to the hydro store and try  using one under a bulb and one under natural light.

California sunlight 9537 lumens at 10:36am not exactly the bright point of the day.

10563 lumens at 11:15am which is brighter then what Cervantes says a 600 can do when hung at 3 feet which is what he says to hang them at to get brightest coverage over the entire 3x3 foot space. p.179



HPS 600 at 3 feet according to somebody you love to quote can only do 10000 max he also says to start seedlings under a 400watt light cause it is most like "the less intense sunlight of early spring" p.131

Quote:

  HOWEVER this is without any ozone, clouds, dust, etc to absorb any of it.


  Since most of us here at this site don't own a space shuttle and take our readings down here on the surface of the earth this doesn't even come into play other then to make your answer seem more complicated then it really is.


and I do know this have a 6 ft plant outdoors and the meter reads the exact same at the top of the plant as it does at the bottom. That doesn't happen under any bulb. Why is that exactly one may just be a little brighter.


So to anybody out there take your light meter and go to the edge of your garden. Take a reading and then take one out in the sun and post your results. Besides what is the best way to learn? Reading crap on forums no matter who is posting it or actually going out and doing it yourself and seeing with your own eyes?


last but not least to get the light to the plants in amounts higher then you would find outside you would have to have every plant the exact same distance from the bulb. Maybe Wiki has a answer for this.


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Invisiblemaryanne3087
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Re: using MH light for seedlings? [Re: Magash]
    #500576 - 11/24/10 03:31 PM (6 years, 12 days ago)

I've quoted Jorge Cervantes once, only for lack of better information which was stated. Never have I quoted Jorge Cervantes and said I hold him in high regard.


Quote:


California sunlight 9537 lumens at 10:36am not exactly the bright point of the day.

10563 lumens at 11:15am which is brighter then what Cervantes says a 600 can do when hung at 3 feet which is what he says to hang them at to get brightest coverage over the entire 3x3 foot space. p.179



HPS 600 at 3 feet according to somebody you love to quote can only do 10000 max he also says to start seedlings under a 400watt light cause it is most like "the less intense sunlight of early spring" p.131


You're comparing the sun to a single light it is very easy to provide more than 600w over a 3x3' canopy I can easily run twice that light which would exceed the suns irradiance capability under any circumstances even if ozone, dust, water vapor, etc were all not a factor (which lowers it's brightness on the surface of earth by over 50%). 3' high is also very high I'd consider that height if using none air cooled reflectors.






Quote:


  Since most of us here at this site don't own a space shuttle and take our readings down here on the surface of the earth this doesn't even come into play other then to make your answer seem more complicated then it really is.






I'm sorry you didn't understand... Those readings would be the same on the surface of the earth if there wasn't any ozone, clouds, dust, water vapor, etc to absorb or reflect any of the light. Solar irradiation doesn't diminish very much which is why we can see stars so far away they may not even exist anymore.

Quote:


and I do know this have a 6 ft plant outdoors and the meter reads the exact same at the top of the plant as it does at the bottom. That doesn't happen under any bulb. Why is that exactly one may just be a little brighter.




Solar irradiation doesn't diminish on such a rapid scale, doesn't have anything to do with brightness.

Quote:


So to anybody out there take your light meter and go to the edge of your garden. Take a reading and then take one out in the sun and post your results. Besides what is the best way to learn? Reading crap on forums no matter who is posting it or actually going out and doing it yourself and seeing with your own eyes?




First hand experience is no doubt valuable to an observer however you obviously have some problems with facts of science. You seem to convince yourself a lot of things that are bullshit are science fact. In actual science people are proven wrong all the time, often by themselves so it shouldn't be surprising that your assumptions are often incorrect. This is subject on solar irradiation is not debatable it's easily observed today and there are literally thousands of papers published by universities that will back up what I posted.

last but not least to get the light to the plants in amounts higher then you would find outside you would have to have every plant the exact same distance from the bulb. Maybe Wiki has a answer for this.

Also not true this almost makes no sense at all. It would not be hard to provide more light than the sun can provide over an entire 3x3 or larger canopy. Some spots would be brighter than others but the entire canopy can exceed the suns output.
Quote:



No the difference between us is I actually grow and do this stuff rather then quote stuff without ever trying it. I'm sure by your answer you don't even own a light meter why don't you try going to the hydro store and try  using one under a bulb and one under natural light.




I actually grow and have been for many years. Much of the stuff I post is from first hand knowledge or is researched from university studies which are nearly in the strictest sense indisputable truth.


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InvisibleInverted
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Re: using MH light for seedlings? [Re: maryanne3087]
    #500615 - 11/24/10 05:59 PM (6 years, 12 days ago)

Quote:

maryanne3087 said:
Quote:

Magash said:
Fuck this drives me out of my fucking mind. Ok, that wasn't meant to be aimed at you but I have no idea where the fuck this seedlings can't handle strong light shit came from. They start in the sun out in the wild. Even mild sun is way brighter then any hid light.





I grow my seedlings under HID also. The sun is not brighter than any HID, it's actually very easy to provide more light concentration than the sun even on the clearest days at high noon even with cfls.

Have you ever seen any leaf bleaching on any cannabis plants outdoors? Probably not. Have you ever seen leaf bleaching on cannabis plants indoors? Probably if you run a lot of watts/m2.

A 600w over a 3x3' canopy has stronger light intensity than the sun (barely), I believe a 600w over a 3x3' canopy is supposed to match the strongest sun light exposure possible in nature. Then considering that the sun is only brightest once a day and there's clouds to block it frequently growers can and usually do provide much more light throughout the day then their plants would get outdoors. Weather or not it's a bit less or a bit more, a grower can choose to provide far more than 600w over a 3x3' canopy if he or she so wishes, which would far exceed the sun's capability.

I believe that a typical meter squared gets 1kw at high noon during summer at the upper atmosphere but much is absorbed by dust, ozone, water vapor, etc and about half of that reaches the ground.




The sun is equivalent to 1,081 Watts of HID light, and obviously you can bleach a Cannabis plant indoors but you'd have to be a complete fool to keep your lighting that close to your plants/canopy...

I would like to see proof w/ pictures of a light meter reading the same output at canopy level under a 600w, and another at the most intense sunlight of the day...  I strongly believe that the sun is going to put up better numbers, however like you say, there are full days of overcast skies, thunderstorms, also from dawn to dusk, the sun starts out weak, becomes intense, then back to being weak before disappearing below the horizon. IMO, if the sun turned on and off like an HID bulb, with consistent intensity, that it would outperform many lighting systems.  However, there are always exceptions to the rules it seems haha


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Invisiblemaryanne3087
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Re: using MH light for seedlings? [Re: Inverted]
    #500619 - 11/24/10 06:07 PM (6 years, 12 days ago)

Even if you find some place with slightly higher nature sunlight than a 600w over a 3x3' canopy I'm certain it won't be much stronger esp throughout the entire day and you can't add more sunlight but you can always add another light.

Magash's claim was the sun can not be beaten by artificial light then the only hope he had to attempt to maintain that claim was comparing sunlight to a limited light source(a single bulb) or a 600w hung at 3'



Edited by maryanne3087 (11/24/10 06:09 PM)


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InvisibleInverted
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Re: using MH light for seedlings? [Re: maryanne3087]
    #500656 - 11/24/10 08:43 PM (6 years, 11 days ago)

Ok I gotcha, I was just throwing my 2 cents out there...


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InvisibleMagashM
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Re: using MH light for seedlings? [Re: Inverted]
    #500677 - 11/24/10 09:54 PM (6 years, 11 days ago)

The reason I chose the 600watt bulb as a reference point is cause you originally posted this line

Quote:

I believe a 600w over a 3x3' canopy is supposed to match the strongest sun light exposure possible in nature.




It does not.

I was working with your numbers. So fuck you when it comes to this line of crap.

Quote:

then the only hope he had to attempt to maintain that claim was comparing sunlight to a limited light source(a single bulb) or a 600w hung at 3'




Just how many cfl's did you plan to use when you said this

Quote:

it's actually very easy to provide more light concentration than the sun even on the clearest days at high noon even with cfls.






Quote:

Solar irradiation doesn't diminish on such a rapid scale, doesn't have anything to do with brightness.




So your saying that light doesn't diminish the further you get away from the bulb because it doesn't under the sun. I'm talking light used by the plant to grow at high noon since those were your numbers. Remember "I believe a 600w over a 3x3' canopy is supposed to match the strongest sun light exposure possible in nature." In order to do that it would have to be usable light by the plant to grow in equal amounts from the top of the plant to the bottom. Not gonna happen with bulbs and if the entire plant gets more light that it can use to grow it's gonna yield more then one that only gets the bright light on the tops of the plants.


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OfflineMidnight
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Re: using MH light for seedlings? [Re: Magash]
    #500680 - 11/24/10 10:04 PM (6 years, 11 days ago)

:popcorn:


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Invisiblemaryanne3087
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Re: using MH light for seedlings? [Re: Magash]
    #500682 - 11/24/10 10:32 PM (6 years, 11 days ago)

Mary-I believe a 600w over a 3x3' canopy is supposed to match the strongest sun light exposure possible in nature.

Magash-It does not

Even if the sun can beat a single 600w over a 3x3' at certain times of day, the averages are probably lower, and the sun is definitely without a doubt not as strong as 2x600w over a similar canopy or a single horizontal and a single vertical. - Fact is a grower isn't limited to a 3x3' canopy with a 600w light Fact is the sun has limitations Fact is there is only one sun Fact is the sun can be beaten without great difficulty.

CFLs can cause bleaching which is far exceeding the sun's output. There's some growers on ICmag who bleached their plants with CFLs and had to cut back. I forgot the guys handle but he has just under 500w of CFL over a 5.4 ft canopy and that makes for over 10 000 lumens a sq ft. So if I wanted to beat the sun with CFLs I would use slightly more?


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