BigCube
- 2,676
- 263
Excellent informationJust a short disclaimer here, I am not an expert. I've done my own research, I will show my sources and I am willing to be corrected.
I will try my hardest to keep my bias out of the equation as best I can.
Light a small portion of the electromagnetic radiation spectrum:
View attachment 924727
https://imagine.gsfc.nasa.gov/Images/science/EM_spectrum_compare_level1_lg.jpg
Within this narrow band of the spectrum is the visable light spectrum.
View attachment 924728
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 380 to 740 nanometers.
This is what we are primarily interested in when growing plants. And what we are measuring when we measure Lumens.
There is a tiny bit leading in to and out of the spectrum that plants can use we know as ultraviolet and far red.
The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total quantity of visible light emitted by a source per unit of time.
Photosynthetically active radiation, often abbreviated PAR, designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis.
So, you might be asking: What's the deal? Both those spectrum's are almost exactly the same. What's actually being measured, and how can we use this information to help us grow plants?
Well in short, they are both measuring the same thing different ways. One is slightly more accurate when dealing with plants.
PAR Is a measure of the actual radiation hitting the sensor, the sensor being a known size, some math is done and you are given a number representing the actual amount of Photosynthetically active radiation. It is relative to a standard formula and thus you have a standard unit of measure.
Lumen is a measure of the visible light spectrum as compared to 1 Candela (Candle).
Lumens are Slightly weighted to the human eye, so it gives more weight to brighter colors.
So you can see, they are both valid unit of measuring light for both humans, and plants. Since they are both measuring the same part of the spectrum, the numbers can be interpreted to denote more or less light on a scale. Par will be a little more accurate as is it measuring the actual radiation hitting the surface and lumens is measuring the amount of visible light of an area.
Higher Lumen counts must equal higher PAR values and vice versa. since they are measuring the same thing, and more is more. Keep that in mind if you've been talking yourself in to buying a costly PAR meter. The only real reason to own a PAR meter, is so you will have accurate PAR measurements. But if more par = more lumens and more lumen = more par. you're just paying for a name. Conversely there are formulas that can give you accurate PAR number from Lumens. Even online calculators that do it for you.
Convert Lumens to PPF - Online Calculator | Waveform Lighting
Online calculator to convert luminous flux (lumens) to PPF (micromoles per second).www.waveformlighting.com
It's not the spread it's just the efficiency difference. In other words LED puts out more ppfd per watt than HID lighting.Could you elaborate on the 30w to 45w led to 60w to 80w HID.
Is it because the HID has a hot spot (less efficient)and the led is spread out (more efficent)?
Could you elaborate on the 30w to 45w led to 60w to 80w HID.
Is it because the HID has a hot spot (less efficient)and the led is spread out (more efficent)?
Yes after much research I found that out. So my LEDs are 35w, my blue and red spectrum are a little above required. I don't have any extra white light running. I have 2 plants under each light, 2 lights. Everything is ok, and that's the problem it's just ok. I just need a number then I can market the rest happen.Lumens are not an accurate way to measure LEDs. Like you have 120 sq ft of space. Using 50 watts per sq ft, you will need 600watts of white lights (TRUE watts)
I run a bit over 70 watts per sq ft myself, and use dimmers when appropriate.
I would say that you will need at least 600 watts of white, and maybe 800watts in flower with Burples. Your present 35 watt lights (what are they?) will not get you anything in flower. It will be easier to help if you can provide more details?Yes after much research I found that out. So my LEDs are 35w, my blue and red spectrum are a little above required. I don't have any extra white light running. I have 2 plants under each light, 2 lights. Everything is ok, and that's the problem it's just ok. I just need a number then I can market the rest happen.
Yes after much research I found that out. So my LEDs are 35w, my blue and red spectrum are a little above required. I don't have any extra white light running. I have 2 plants under each light, 2 lights. Everything is ok, and that's the problem it's just ok. I just need a number then I can market the rest happen.
I've got all that, I'm trying to figure out what my ppfd should be for my space? I have pages of calculations for watts to lumens, for lumens per sq ft, for my PAR. I know I have 630.34 umol/s in a 10×12×10 space. I'm brain locked from the math, maybe im not looking in thet right place to find my answer. Can someone help, am I running enough light?
For me, 35watts per square ft would be the high end with my HLG quantum boards. I normally run 25-30 watts per square ft in flower and a little less in veg with very good results. I could prob turn them up some if I was maybe using co2.You need 35w per square foot of grow space. Not per plant. If you're in a 2x4..
2 x 4 = 8 x 35 = 280. You need a minimum of 280w of led light.
3x3=9x35=315w
4x4=16x35=560w
Minimum. You will find the numbers quite respectable.
Now that you understand the numbers, what they mean and how to use them. Lets look a bit closer at the light itself.
View attachment 924729
Most people don't need to be told that white light is made of all the colors in the visual spectrum. what may not be obvious to some people is that "white" light has quite the range usually expressed in a temperature (kelvin ) Normally ranging from around 2500k to 6500k. What this relates to visually is a warmer or brighter light Caused by more red or blue in the spectrum.
It's not as simple as this, but in general. Plants like to have more blue in Veg, this causes them to stretch up and out and gain height and width. Generally promotes farther node spacing and less foliage growth. In Flower they prefer a more red spectrum. This causes them to bush up, get tight node spacing and grow more foliage.
For these reasons some growers use a Bluer spectrum (5000k to 6500k) in veg and a red-er spectrum in flower (2700k to 3500k). But equivalent results can be had by both flowering and vegging under the same light. In some cases, people go right in the middle with 4000k and have great results.
Personally I prefer 2700k to 3000k cause veg isn't as long as flower and I like bushier plants with shorter node spacing.
Green yellow and orange also play their part. It differs from plant to plant, but things like leaf thickness, flavor and leaf color are some of the factors the other spectrum's can affect. I am far from a scientist, and am just begining to grasp this aspect of lighting, as are most scientists. A good introduction to it can be found here:
In the first minute of the vid he is speculating about why people thought that plants don't use green light (his attitude seems to be that it is because they are dumb) and totally missing the obvious. THE PLANT APEARS TO BE GREEN BECAUSE IT IS REFLECTING ALMOST ALL OF THE GREEN LIGHT!!!! When you look at something, actually anything, it appears to be a certain color because it is absorbing all of the colors except the one which you see. This is a very basic concept and does not need to be made confusing with long arguements. I use a green headlight all the time in my garden because the light is off when I am awake and vice versa. I have not gotten re-veg or even nanners because of it. In fact my only experience with nanners has been on feminized plants, though I know it can happen with regular seeds. With regular seeds it is usually because of bad breeding or someone flowers it too long and the survival of the species gene kicks in.
Sorry for the rant, now back to your regularly scheduled programming lol.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?