Full Spectrum 3000 Kelvin vs 5000 Kelvin

[Jason]

Don't mean to be a twit, but I keep seeing LED lights that give off 3000 Kelvin light described as "full spectrum". My understanding from other disciplines that I work with is that 5000 Kelvin is considered
full spectrum, as it more closely mimics real sun light.
Wiki has an informative blib if you search "Full Spectrum Light".
Here is part.
Use in gardening[edit]

Gardening under lights keeps plants blooming almost year-round, for a wintertime harvest. Grow lights are specifically intended to support plant growth, although with varying degrees of success and energy efficiency. Some plants grow better when given more of a certain color light, due to the mechanism of photosynthesis. Specifically more blue wavelengths enhance vegetative growth and development, while the addition of increasing amounts of red light enhances budding, flowering and fruiting.

3000 Kelvin lights do not give much red spectrum. 5000 Kelvin lights do.

I also like the fact this Wiki blib points out that there is no technical definition of "full spectrum". It's sales copy for the most part.

"Full-spectrum" is not a technical term when applied to an electrical light bulb but rather a marketing term implying that the product emulates natural light.^[1]


Not trying to get anybody's panties in a bunch. Just thinking vocabulary should support our efforts not muddy the conversation.

If you bump around Wiki a bit, they have other articles that are more technical and fun to read.

I like the burning carbon cube and its temperature re light given off as the source for the Kelvin designation. I wonder who heated one of those suckers up to 5000 Kelvin to see it turn sun bright.

[dontknownuttin]

My bulbs are 10,000K MH for veg and a HPS bulb for finish

[Jason]

Thank you for posting.

I saw a chart on Wiki that listed Kelvin values from very low to close to that level.
I don't know how much of anything above 5000 Kelvin is absorbed and used by a plant, as its not natural light. Maybe in outer space, but fortunately, our atmosphere filters it for us.
Nothing between 5001K and 10,000+K was involved in flora evolution.
I could guess your plants love the stuff they evolved with. And all other spectrum's sort of go un-noticed, un-absorbed or something.

I just wonder how many companies are selling Ferrari;s to people driving to the grocery store.
If 4 cylinders get me there, I'm good. 12 cylinders won't get me there any quicker or better due to stop signs and stop lights, ie lack of absorption.

It's not what you give them, it's what they can use. Like pH and nutrients.

So what did those beauties cost and how much area do they feed?

[Weed Pharma]

When I contacted Marshydro and looking at reviews a year ago- what matters is the spectrum the plants see- not humans.

The actual LED are predominantly red or blue (with a handful of other diodes) in different proportions depending on a veg or bloom setting for the Reflector series.
I have in the past, added MORE red in bloom, but didn't notice a difference, so I don't bother.

The PAR values were great- so that's all that mattered to me and I have been glad with my choice to use LED grow lights.
I'm always open to proven theories to increase yield without increasing costs and lights are only a small part of growing.

[Jason]

You are 100% right. Feeding a plant light it can't "see" or absorb is pointless. Light manufacturers have no problem selling us lights with spectrum's that are useless to plants but make PROFITS for them.
Humans often value things based on numbers. Higher is better. Bigger is better. Taller is better, more spectrum is better, etc. In many applications, such things are not always beneficial.

Do you mind posting Kelvin temps for your lights, area covered and costs?
I'm in my first hydro grow. Its going very well. I have (2) red. white. blue LED's, 300 W, described as full spectrum. Before I bought them, I read that in order for an LED to be full spectrum, meaning 5000K, it had to have the three color diodes. For $60-70 USD, I took a chance. It worked, so I bought another.

I work in a number of specialties. Computer animation, CAD, photography, 3D printing and others. I tend to stay away from vendors , where ever possible, that sell market specific goods as they are often WAY over priced. Look at jewelry tools, then look for something similar or identical tools not marketed to jewelers. Often by the same maker. You will save a lot of money.

For a cost conscious person a little research can save a lot of money with no loss of benefits.

Thank you for posting. I'm very interested in the conversation.

By the way, how did you confirm the information from Marshhydro? I always distrust single source information. Unless its on Fox News.
Just kidding. I think I had that channel deleted......

[Weed Pharma]

Jason -When Marshydro changed from a 3w diode to a 5w diode- there were reviews in magazines and a couple of tests with PAR meters on YouTube (not by Marshydro).
As well as, several comparison grows.
My cost per gram is low and my yields are just under 1g per watt- draw from the wall.

[Jason]

I'm on my first hydro grow, so I have no numbers about yield, grams per watt, etc. Yield is not a factor in my strain choices. This is a hobby with no income desired. I expect to give most of it away. But I'll track that, as I like to document and keep records.

[OzBud]

I use a 2100K HPS bulb start to finish.

[007]

3000 Kelvin lights do not give much red spectrum. 5000 Kelvin lights do.

That is 100% backwards. Red light is lower on the K scale. 3k is an HPS color (flower), whereas 6k is a MH color (veg). Red is higher on the visible spectrum scale, not the Kelvin scale.

[Jason]

I really didn't make this up. Is this graph just totally wrong?

[007]

This is a light spectrum scale, not a Kelvin scale. Measurements in light spectrum are made in nm.

[Jason]

Yes, it is an nm graph showing 5000 K. Like if you used a prism, this breaks 5000 K into colors (nm) and shows you whats there. Nm is along the bottom.
Lots of red.

[007]

This is a Kelvin scale

[Jason]

Right. And if you took the color shown at 5000 Kelvin, and broke it into its constituent nm's, you would see the graph above.
This does not show the spectrum within each Kelvin temperature shown.
Look at the cover of Pink Floyd's Dark Side of the Moon. White 5000K into the prism, rainbow (full spectrum) out.
Kelvin tells you the spectrum temperature to look at for the nm's you need for your work.

[Green75]

Full spectrum has all colors...

[Sonnyhad]

Right on Green~~

[Jason]

This is an excellent illustration of why "full spectrum" really has no technical meaning, particularly when applied to a specific need or situation.
These graphs show the peaks and valleys of lights that have quite a range of nm's. I use a number of full spectrum lights for various, non agricultural, applications.
In one, I use a full spectrum reptile heating light, as its very strong in the 380-405 nm range that I need for that application. For product photography, I use a totally different full spectrum light set up, CFL and LED. . For growing I use another tri color LED full spectrum light. The grow light and reptile light would be useless for photography. All are accurately described as "full spectrum". And each is matched with application and nm output.

[Jason]

Point being, be informed, buy what you need. Look at the spectrum/Kelvin charts for your purchase.
I think we're all happy with the results we see from our lights.