Introduction to Lighting

[jjng5]

Great guide. Is it possible to use too much light on seedlings? I have 6 seedlings growing under 7 26W CFL's and they have been yellowing. Is it best to start of with only a couple bulbs and work your way up?

[jzchillin]

Originally Posted by jjng5

Great guide. Is it possible to use too much light on seedlings? I have 6 seedlings growing under 7 26W CFL's and they have been yellowing. Is it best to start of with only a couple bulbs and work your way up?

generally with cfl's the more the better. at the moment i have 4 seedlings in rockwool under 2x200w cfl's and they could take more. i keep them typically about 2 inches away, even though they do get a little warm, i'm not really worried about it. i think the yellowing might have something to do with the ph, your soil type or a combination of both. if you are referring to the first petals (the name escapes me) that appear, they usually turn yellow and die. the cfl man i have followed in this forum is Kamel, Kamel's CFL Guide - Grasscity.com Forums. he has alot of cfl grow info in his journal.

[jzchillin]

Originally Posted by IMgreen

yeah it is!

the light distance chart is kinda handy too, do you have it?

sorry for not getting back to this. i have the hps lighting chart but not the mh. you or anyone is welcome to post it in here if you have it.
FC-Chart-HPS.jpg
i think this one is kind of cool too.
light output comparison chart.jpg

[jzchillin]

been awhile since i added anything. if anyone has anything to add feel free...

[kangasaurus]

Does hight of the plant matter? What I mean is, you say that 250W HPS is good for 2'x2' grow space, but does the height of the plant matter? I've read places that, not specific to our favorite plant, the taller the plant, the more wattage you need. So for a 2'x2' grow space with three 4' tall plants, would I need more along the lines of 400W HPS?

[jzchillin]

Originally Posted by kangasaurus

Does hight of the plant matter? What I mean is, you say that 250W HPS is good for 2'x2' grow space, but does the height of the plant matter? I've read places that, not specific to our favorite plant, the taller the plant, the more wattage you need. So for a 2'x2' grow space with three 4' tall plants, would I need more along the lines of 400W HPS?

If you have a cool-tube or are able to keep the temps down you can use a 400watter, but the plants can get radiation poisoning (sounds strange but it is true), if the light is to close regardless of temps. in the case of a 400watter, i don't see that problem. i personally, have used a 600watter, with a 900cfm fan to cool it, in a 3'x2.5' box. in a box, the height of the plant doesn't really have an effect on the wattage. everything about 10in below the canopy will die away and only the tops will get the light. 1 thing to note, the stronger the light, the further it will penetrate the canopy and the more dense your buds will be. i have a light penetration-wattage chart somewhere i'll post.

in a room that size i would use a 400watter in a cool-tube

[Ktema]

Thanks for the info!

[jzchillin]

Originally Posted by Ktema

Thanks for the info!

Anytime bro!

[jzchillin]

Seems to be a lot of mis-information out there. Blind Leading the Blind. bump....

[cantharis]

What are the units nW ???

Are you sure that is not meant to be nm - nanometres - in which wavelengths of light are usually measured. nm or Angstrom units.

[jzchillin]

Originally Posted by cantharis

What are the units nW ???

Are you sure that is not meant to be nm - nanometres - in which wavelengths of light are usually measured. nm or Angstrom units.

NanoWave. Oldschool phsysics term. NanoMeter snuck it's way in as a measure of unit called the Millimicron (mµ), as a way to measure a lightwave form. Since all light is a wave form and nano is a form of measure then a nanowave is the measure of a specific range of light. A really really really tiny-itsy-bitsy wave in the spectrum.
EDIT: But essentially is the same thing referred to as NM, just without the explanation. When your talking about light it is a given what you are talking about but NM can be used for measuring anything.

[cantharis]

Originally Posted by jzchillin

NanoWave. Oldschool phsysics term. NanoMeter snuck it's way in as a measure of unit called the Millimicron (mµ), as a way to measure a lightwave form. Since all light is a wave form and nano is a form of measure then a nanowave is the measure of a specific range of light. A really really really tiny-itsy-bitsy wave in the spectrum.
EDIT: But essentially is the same thing referred to as NM, just without the explanation. When your talking about light it is a given what you are talking about but NM can be used for measuring anything.

Nanowave? As a former teacher of physics I have never heard of this. Neither will anyone else familiar with SI units, where W is the abbreviation for watt, the unit of power.
And nanometer is just the standard prefix nano-, meaning 10 E -9, applied to the basic unit of length.
And red light is in the wavelength 600 - 700 nm (please note, correctly expressed as lower case, not the upper case that you have erroneously used). Sorry, this NW is a nonsensical expression - I think it is just a typo that has crept in.

[ocitown]

Originally Posted by jzchillin

Attachment 101185Attachment 101186Attachment 101187Attachment 101188Attachment 101197
The diagrams above shows the full range of light and where each type of lighting system falls within that range. Artificial lights produce just a slice of the full range. This leads to much discussion and experimentation to determine which, or which combination of lighting is best for a particular crop.

Lets establish a reference point to work from, examine several types of lighting and put this information to practical use.

Reference point: For most of the daylight hours, the outside daylight peak is centered on 5500 degrees Kelvin (refer to the above chart).

Metal Halide: These lights emit a light on the bluish side of the spectrum. They are considered a grow light and it is considered that they produce a more stalky vegetative type of growth in plants. These lights are commonly used throughout all phases of plant growth and produce excellent results.

Agro Sun Halide: Agro Sun is a hybrid halide bulb that generates extra red light for flower and fruit production.

Sodium Vapor: Sodium vapor lighting is way down in the red. There is some indication that the spectrum produced by these lights promote flowering.

Thanks to ik3002 for extra info!

Did quite a bit of research on finding just the right MH with the best blue spectrum 5500K and found even though your chart states the MH are 5500K. they are found mostly at the 3800-4200K. range.

I found one which i use that is a true growing MH 1K which is 5500K.

If you could please link us to some others i would like that as my Blue bulb only has an 8000 hr life and was VERY expensive,results are worth it IMHO even if its my only choice.

[vtx]

Age old debate:

Is it the wattage, or the lumens that matter.

With CFLS they brag about being 100 watt equivelant, in that they put out as many lumens as a 100 watt bulb, but only use 23-30 watts.

As far as my knowledge goes, wattage is just a measurement of energy, and the lumens are light so:

is it 100 watts plant, or 2000-3000 lumens per plant?

[ocitown]

Originally Posted by vtx

Age old debate:

Is it the wattage, or the lumens that matter.

With CFLS they brag about being 100 watt equivelant, in that they put out as many lumens as a 100 watt bulb, but only use 23-30 watts.

As far as my knowledge goes, wattage is just a measurement of energy, and the lumens are light so:

is it 100 watts plant, or 2000-3000 lumens per plant?

Because of other variables its said that each plant needs 50-100 watts and 3000-5000 Lumens IIRC to fully mature a plant to the end.

BTW,you should use the actual CFLs watt rating not its equiv.