Lighting & Lumens

Lighting

Light is needed by a plant for using nutrients and manufacturing food. It has a great influence on chlorophyll production, growth rate, leaf size, and flower and seed production. Light will be one of the most important aspects of your grow operation. For the purposes of growing marijuana, there are two basic types of lights: fluorescent's and high intensity discharge (HID), including MV (mercury vapor), MH (metal halide), and HPS (high pressure sodium).
HID vs. Fluorescent

The main difference is that fluorescent's create light by passing electricity through a gas vapor under low pressure and HID creates light by passing electricity through a gas vapor under high pressure. HID lights are much brighter and while initially more expensive, are more cost efficient to operate and will grow a much nicer crop. Therefore, they are the light of choice for most indoor growers.
Fluorescent

Fluorescents come in a wide variety of shapes and sizes. There are compacts, twist bulbs and circle bulbs. They all work the same way. They have a starter and ballast which help provide a steady and regulated amount of electricity to the light. Before HID lights were available indoor growers used fluorescent lights. While fluorescents can be used for an entire grow from seedling to harvest, it is generally not advised to use them in this way. To grow effectively with fluorescent's, think small. These lights are better suited for starting seedlings, rooting clones and small plants, maintaining moms for cloning purposes, and providing sidelight for the undergrowth. These situations do not require a high intensity of light to run their course. The light emitted by fluorescents is gentler and more diffuse, it doesn't release a lot of heat, and doesn't make the plant work as hard. For this reason they can be kept closer to the plant. One or two inches is sufficient, but this also means that the lights must be adjusted almost daily to accommodate growth which can be troublesome.
High Intensity Discharge

There are basically three types of HID lights. Mercury vapor (MV), metal halide (MH), and high pressure sodium (HPS). These lights also require a starter and a ballast.
Mercury Vapor

Mercury vapor is the type of lights that were used for streetlights many years ago. Not very good for growing because it doesn't provide enough of the right kind of light spectrum. While they do provide a littleof the blue spectrum, MV also produces too much heat to get very close to a plant, and are very inefficient to operate.
Metal Halide

The metal halide is a very good source of the white/blue spectrum of light that is ideal for vegetative growth. Many growers use MH during the vegetative phase. MH is bright and cost efficient to operate, but not as efficient as HPS lights. Most commonly used sizes are 400 watt and 1,000 watt. Works best when used in combination with HPS lights.
High Pressure Sodium

The best light available today for growing marijuana. High pressure sodium lights are very bright and very efficient. This light has a red/orange spectrum that is ideal for the flowering phase. With enough of these kind of lights you too can grow those centerfold buds. HPS comes in a wide variety of wattages from 70 watts up to 1,000 watts.
Lighting Forumlas

To correctly determine the best lighting for your space there are several things that you have to know. At this point, a couple of definitions are in order. The amount of light emitted by one candle that falls on one square foot of surface one foot away is called a lumen (lm). The amount of electricity flowing through a wire is measured in watts. Watt (W) hours measure the amount of watts used in one hour. A kilowatt/hour (kWh) is 1,000 watt/hours (Wh).
Lumens Per Square Foot

To determine how many lumens per square foot you have, find out the square footage of your space by multiplying the width and depth. Divide the lumens available by your square footage. This will give you lumens per square foot. For example, say your space is 3 feet deep by 4 feet wide, for a total of 12 square feet. The total lumens available from your light(s) is 45,000 lumens, which means you have 3,750 lumens per square foot.
How Much Light Do I Need?

Technology has advanced so much in the last 15 years that we are constantly refining the process and updating what we know works best for growing. Current theory holds that the minimum amount of lighting needed to sustain growth is around 2,000 lumens per square foot. Mid range is around 5,000 lumens per square foot. Optimal is 7,000 to 7,500 or higher lumens per square foot.
Can I Have Too Much Light?

The basic answer is no. According to the law of diminishing returns, you could theoretically reach a point when your plants just couldn't absorb any more light, but it would be impossible to have that many lights in your space. Heat from the lights would become a problem long before you ever reached that point. So use as many lights as you want, just control the heat.
Experimentation is the only sure method to determine the best solution for each plant. If plants are not receiving enough light, they begin to grow tall and spindly as if stretching for the light and foliage becomes pale green. Or, if they need to be moved closer to the light, or given a longer light exposure period. Too much light may lead to bleaching of leaves and flowers, browning and shriveling. Leaves would become overly compact and curl under at the edges.

Whilst any attempt to inform and advise newer growers to the complexities of plant light requirements should be applauded, to produce such a dogmatic one-eyed view of the situation in favour of HID and HPS systems, with no thought given at all to new lighting devlopments and techniques is almost as bad as producing no guide at all.

To say that HID and HPS systems have become the indoor growers lights of choice is perfectly true, but that's only because up until recently they were the only viable options in terms of sheer lumen output that growers had - there are other choices now with recent compact flourescent developments. To simply write off flourescents as only good for seedling, rooting clones and small plants is to completely ignore these current and recent developments.

Compact flourescent lights (cfl) can and do offer a very viable alternative to HID and HPS systems in many smaller grower situations.

There are three distinct disadvantages to HID and HPS lights in relation to the newer cfls -

1) They're more expensive to run in terms of wattage used;
2) They produce a lot more heat build up, requiring more expensive and sophisticated extraction and ventilation systems;
3) Whilst lumen output is high, a lot of those lumens are lost through not being the correct light spectrum and having to be positioned so far away from the tops of plants due to the heat. The further away a light is from its target the less lumens it receives.

The new Envirolite compact flourescents overcome the traditional drawbacks to flourescent lights by providing much higher lumen outputs than have previously been available, but just as importantly provide the correct colour spectrum output in the two versions available for vegetative and flowering growth. In other words, all the lumens you get with envirolites are used by the plants. Current Envirolites come in two sizes and two 'colour temperatures' -

Blue for vegetative growth (350 – 500 NW) in 125w (12,000 lumens) and 200w 18,000 lumens)
Red for flowering growth (600 – 700 NW) in 125w (12,000 lumens) and 200w (18,000 lumens)

The other advantages to these Envirolites is the ability to position the lights inches away from the tops of plants due to the much lower heat output - thus the plants receive all the lumens available.

It's not hard to see that by using 2 x 200w Envirolites positioned close to the tops of plants can produce a lumen output of around 36,000 lumens, which compares very well to that of a standard 400w HPS or HID system outputting 50,000 lumens but having to be positioned 2 feet away from the tops of the plants. Not only do the 2 200w Envirolites provide a similar lumen output to the 400w hps (when distance is factored in) they're also cheaper to run and produce far less heat output.

It's fair to say that the cost of a 2 x 200w Envirolite system (2 x 200w blue and 2 x 200w red) + hood is probably around 30% more expensive than an equivalent HPS system, that extra money is easily recouped by the lower operating costs in terms of wattage used over a period of their use.

Don't dismiss Envirolite compact flourescents so easily - they do provide a very viable alternative to the more common and widespread use of HID and HPS systems.

Another post that needs to be a "sticky."

Vi

Nice info m8....

Reserving this spot

-=UNDER CONSTRUCTION=-

I disagree with "They're more expensive to run in terms of wattage used". I switched from hps to t5's and saw a big jump in my electric bill. We are talking a $20 plus increase. I was told that the t5's would decrease my bill because I didn't have to run that mean old energy sucking hps and it's ballast. What a bunch of crap.

mogie said:

I disagree with "They're more expensive to run in terms of wattage used". I switched from hps to t5's and saw a big jump in my electric bill. We are talking a $20 plus increase. I was told that the t5's would decrease my bill because I didn't have to run that mean old energy sucking hps and it's ballast. What a bunch of crap.

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Are u running the same wattage at the same period of time during the same hours of the day????

wattage slightly higher
running 4 hours a day less
surprized by the amount of heat the t5 puts off

some may find this useful

Very good info thx.. I would like to use Flourescent myself...

This ties into another similar question I had: Is babygro saying that regardless of HPS being the most efficient light (most lumens per watt used) the majority of the light is not being used by the plant (at least in the veg stage), and therefore using a 'less efficient' light that has more light in the correct spectrum, such as cfl's, you are actually getting more bang for your buck?
Is it better to use cfl's as opposed to HPS (with added blue spectrum 430 W) during veg stage?

I am considering getting one or two cfl's for veg so some input would be very helpful.

The right spectrum is key and weather its Metal Halide (High Intinsity Discharge - HID) or CFL @ 4,000-5,000 Kelvin, they are the right spectrum for growth. High Presure Sodium - HPS, also a HID bulb, is used for Buding @ 6,100>< Kelvin as well as the same spectrum of CFLs.

Sorry if ilegeble; its X-mas Im Drunk and Stoned

splifman said:

This ties into another similar question I had: Is babygro saying that regardless of HPS being the most efficient light (most lumens per watt used) the majority of the light is not being used by the plant (at least in the veg stage), and therefore using a 'less efficient' light that has more light in the correct spectrum, such as cfl's, you are actually getting more bang for your buck?

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That's essentially what I'm saying yes, but it depends entirely on the HPS bulb you intend using, and how much of the blue spectrum they output. What makes HPS bulbs so good for the flowering stage (large amounts of the red/orange light spectrum) conversely makes them inefficient when used for vegetative growth because a lot of the lumen output is in the wrong light spectrum.

There's an enormous amount of misinformation put out about the large lumen outputs of HPS and Halide bulbs by people who don't understand the difference between lumen output and PAR output. PAR stands for Photosynthetically Active Radiation and refers specifically to the main portion of light as used by plants which is between the 350 - 700 nanometers wavelength - this wavelength region is called the 'PAR zone'. Lumens on the other hand along with lux and foot candles is a measurement used specifically to measure light as seen by the human eye which is a smaller wavelength band than that which plants can see and is between 525 and 625 nanometers.

Plants require light in the specific nanometer wavelengths for different aspects of their growth. The blue/white light spectrum between 350-500nm promotes chlorophyll production, cell activity, stomata movement and makes the plant follow light. The green/yellow light spectrum between 500-600nm is largely ignored by plants (coincidence that this wavelength is almost identical to the lumen measurement system as seen by the human eye?) and the red/orange light spectrum 600-700nm enables plants to make sugar from co2, promotes chloropast production, signals light and dark times and promotes flower and bud growth.

It's not that hard to see that the 500+ wavelength contains very little blue and is mostly yellow/orange/red in the light spectrum, and is therefore not particularly efficient for vegetative growth. This is why you need to check on the HPS bulb you intend using for vegetative growth and exactly how much of that sub 500 nano wavelength it's outputting.

The envirolite range of compact flourescents output light in exactly the right PAR spectrum that plants can use. The blue between 350-500nm and the red 500-700nm.

You can have as many lumens as you like, if they're in the wrong light spectrum - they're all wasted because the plant cannot see them or use them.

mogie said:

I disagree with "They're more expensive to run in terms of wattage used". I switched from hps to t5's and saw a big jump in my electric bill. We are talking a $20 plus increase. I was told that the t5's would decrease my bill because I didn't have to run that mean old energy sucking hps and it's ballast. What a bunch of crap.

Click to expand...

The last time I looked a T5 Flourescent is not the same as a 200w or 125w compact flourescent envirolite, so perhaps its not wise to make a cost comparison with a light you haven't actually used.

PAR lumens have always been what we're looking for, that's why we use Hortilux, or some other lamp for 5 times the cost. The question would be, how does envirolight compare to hortilux, watt for watt, on PAR lumens.

And I find it hard to believe that envirolight's spectrum is entirely in that small range, or else we wouldn't be able to see it, right?

potroast said:

PAR lumens have always been what we're looking for, that's why we use Hortilux, or some other lamp for 5 times the cost. The question would be, how does envirolight compare to hortilux, watt for watt, on PAR lumens.

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Well it's a good question, and not one I can answer with any assurity due to lack of available data, but I did come across a light spectrum graph for an Eye Hortilux 1000w HPS bulb, with enhanced blue light and it's not that hard to see that there's an awful lot of light being output from that bulb that is entirely in the wrong spectrum (Green/yellow 500-600nm) which plants do not use. In fact from looking at the graph, and combining the areas that the plant can actually see and use (the purple, blue, orange and red areas) and comparing them to the areas the plant can't see or use (the green/yellow) areas, it's fairly easy to see that you're probably only getting about 50% of the total light intensity from that bulb that is plant 'useable' light'.

What's also interesting and what supports what I said earlier about lumens being a measurement of light the human eye can see compared to PAR, is that the highest light intensity from that Hortilux bulb is in the 500-600nm (yellow green) area which the human eye is most sensitive to, which accounts for the relatively high lumen output of those bulbs. The PAR areas as mentioned above are nothing like as intense, which means you're not getting a lot of PAR watts for your money.

So, from a HPS bulb outputting say 100,000 lumens only about 50,000 of those lumens are in the right PAR light spectrum and straight away you're paying for 50% of light energy that the plants aren't using. Now factor in that HPS bulbs used without any air cooling need to be positioned at least 2 feet away from the plant tops and you lose even more lumens due to the 'inverse square law' of light intensity. Light Intensity = Light output divided by distance squared. So, at one foot away our 100,000 lumen bulb is only producing 50,000 lumens the plants can actually see, at two feet away, the lumen count quarters (50,000 divided by 2 x 2) = 12,500 lumens.

So from a 100,000 lumen bulb, at the plant tops they're actually only getting 12,500 lumens of PAR light, and people question the vailidity of compact flourescents such as Envirolites that output 12,000 (125w) or 18,000 (200w) PAR lumens and can be positioned inches away from the plant tops, due to their low heat output? That's not to mention the fact that the 1000w system costs more than 5 times that of a 200w Envirolite to operate.

I don't really mind, nor do I care that people use MH or HPS systems and pay an awful lot of money in running costs that is wasted, what I do mind is people promulgating misinformed information about the relative merits of MH and HPS systems in comparison to CFL's like Envirolites, purely on the basis that MH and HPS systems must be better because they output more lumens and people have always used them therefore they must be the best. This is typified by the poster earlier who was complaining that his T5 flourescents cost more to run that his 400w HPS system, this isn't really that surprising is it when you consider that standard flourescent tubes are highly inefficent to run in terms of lumens per watt. A 40w Growlux flourescent tube outputs about 22 lumens per watt when compared to Metal Halide and HPS systems that output between 100-150 lumens per watt depending on system type. There's no legislating for ignorance and stupidity I'm afraid.

potroast said:

And I find it hard to believe that envirolight's spectrum is entirely in that small range, or else we wouldn't be able to see it, right?

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The human eye can detect light in a fairly wide light spectrum at least as wide as the light spectrum that plants can see, but is most sensitive to light between the 500-600nm range. When we see light intensity it's between the 500-600nm spectral range.

i have a thought on this aspect of "usable" light spectrum.... if any of you guys did film or photography work you may have come across a gel that is used on lighting equipment to change the color temperature... they're called CtO and CtB for color temp orange and color temp blue respectively.... it's used to slightly change the kelvin reading and how warm/cool the color of the light is with little intensity loss in terms of footcandles....

i'm wondering if to enhance budding and an HPS bulb isnt an option, could one take a daylight or bluer outputting bulb, or even the green/yellow spectral bulbs, and then gel it (gels are extremely heat resistent dont worry about that) to the orange color that flowering plants love.....

gels cost like pennies in comparison to HPS bulb + ballast + fixture etc

worth debating at least.... any thoughts?

Babygro can you show us a couple pics of the big fat dense buds you grow with enviros?

MajoR_TokE said:

Babygro can you show us a couple pics of the big fat dense buds you grow with enviros?

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The point I've been making that still appears to be somewhat lost on you is that in many peoples circumstances and situations the CFL Envirolite can produce perfectly acceptable results at a fraction of the running cost of a MH or HPS system. You may have plenty of money to invest in perfect results, that's fine if it works for your particular situation and you don't mind throwing a lot of money down the drain on wasted light plants can't use, many people aren't in the same situation and want acceptable results on a budget with the minimum of running costs. Perhaps you might like to bear this in mind the next time you attempt to write a newbie guide on plant grow lights.

I commend your dedication to providing newbies with a useful guide to growlights, but if you slant it so heavily in favour of the system you consider to be the best (for your own particular situation) any such guide ceases to be useful to newbies because of the bias of the author. Far better to put forward all the various alternatives and options and let the newbies themselves decide which is best for their own particular situation - and it's this, and this alone that I objected to in your guide and have attempted to provide information on alternatives that newbies might want to consider using.

Babygro i don't know where you live but where i live i can go to the local hyrdo store(within 5 city blocks from me). Buy a 400w HPS ballast kit with a hortilux bulb for less then $150 canadian, i don't consider this expensive. Many people have had good resuts flowering with cfl's, but these a small grows and the quality isnt as good in my opinion. watt for watt hps put out the most lumens.