lighting A Small Indoor Hobby Grow and Considerations on the Subject of Horticultural Lighting.

I've been using a small grow tent to raise cacti seedlings using 84 watts of LEC or CMH light per square foot with a Sun Systems 315 watt Light Emitting Ceramic grow light and bulb.

The high light intensity and high temperature of my grow tent were ideal for cacti but when I put a few Capsicum plants in there I observed some leaf burn and signs of stress.

I had been thinking of building a 4x4x6' PVC frame and using it to hang some panda film Mylar sheeting from it to make a new box with nearly 20 watts per square foot light intensity however instead of this I chose to use materials I had on hand.

This is what I ended up doing:
P_20201102_221825_vHDR_Auto.jpg


This grow box is actually a steel shelf that can hold up to 5000 lbs with 1000 lbs on each shelf equally distributed. The floor dimensions inside it are essentially 2x4' for 8 square feet total making the watts per square foot value a little less than 40. Although that's brighter than what I had planned it falls right into the upper range (30-40W/sq') of HID light intensity recommendations found in various threads here at the forum.

Another perspective:
P_20201102_221838_vHDR_Auto.jpg


I used a couple of 2x10' Mylar bubble wrap type insulation rolls as the primary reflective surface with some white Styrofoam as well. I have two more shelves of this type in my garage and I didn't need a couple of the stainless steel grid panels for those shelves so I used a bunch of zip ties to use those grid panels to reinforce the sides of the grow unit and I used one panel from the unit as a back wall for the growing space. I used zip ties to hold the Mylar pieces onto the steel grids and for the front piece of Mylar that serves as a reflective curtain I used a few adhesive Velcro-like fasteners making it easy to remove and replace for access to the box.

This next photo shows the Velcro-like product, it is made by 3M and 4 of these little guys can hold 16 lbs according to the manufacturer. That's 4 lbs each and the front piece of Mylar insulation only weighs a couple of lbs at most:

P_20201102_233711_vHDR_Auto.jpg


I will add a bit more Mylar later and remove the styrofoam panels I am making do with currently.

In this next photo you can see a shelf grid I zip tied to the outside of the shelving unit to reinforce it and to form an open front box shaped cage:

P_20201102_231653_vHDR_Auto.jpg


I hung the lamp from the steel grid of one of the upper shelves. The lamp has a built-in ballast so there is it's weight and heat output to consider and the shelves are sturdy and don't trap heat or restrict air movement. I put a small fan inside the box hanging from the same shelf as the light and it both circulates air in the box and pushes it out into the room so the heat doesn't build up.

In this next photo you can see the back shelf panel, and the light and fan hanging from the shelf that forms the top of the inside of the box:

P_20201102_231738_vHDR_Auto.jpg


At the moment I put a couple of pieces of Mylar on the lower inner shelf to create a water repellant uniform flat surface although I will likely replace it with something that can actually hold a few inches of water without leaking so that I can bottom water and drench from the top to leach out fertilizer salts as needed if and when they accumulate in the media.

Right now the plants I have in the box include some super-hot specimens and a Tabasco in #3 nursery containers. I don't plan on keeping these plants in there for long and will mostly over winter them in the garage by a window. For this season I plan on using recycled 32 fluid ounce polypropylene yogurt containers in the box. I should be able to fit about 50 of them in there and for my breeding project I tentatively want about 3 pots each of 15 varieties for a total 45 pots, which should fit without problems.
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For the purpose of setting up an indoor growing environment it is important to carefully consider lighting options. The next section of this post deals primarily with considerations about lighting and common myths about lighting for plants and how the information recently made available about lighting has illuminated several widespread beliefs about lighting and revealed them to be misconceptions based upon primitive and outdated information from earlier studies on photosynthesis. Lastly some links are provided for educational purposes that pertain directly to the recent advancement of knowledge about horticultural lighting, photosynthesis and the effects of, plant responses to, and the utility of different frequencies of light both alone and in combination. Please be warned that for many people much of the following information contained herein may seem controversial because it contradicts various widespread beliefs, claims and concepts about horticultural lighting that are based upon somewhat primitive, outdated and incomplete information that resulted in what we now know was a flawed understanding of the biology of photosynthesis. I ask you to please consider that, for the most part, until further information on the subject became available through and from recent studies... what we now realize to be misconceptions were based upon the best information available at the time those misconceptions became widespread. At present these misconceptions and mistaken beliefs are still widespread and form the basis of what many people think they know about the subject of plant lighting. If you are among these people please do not take the presentation of this information personally.

Thanks,
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Considerations on the Subject of Horticultural Lighting.


It is important to note that the light from bulbs of Light Emitting Ceramic (aka Ceramic Metal Halide) is not safe to to be exposed to. It is very much like sunlight with spectrum that includes Far Red, UV-a and even some UV-b and it isn't healthy to repeatedly and continuously expose eyes and skin to such light however the same spectral components that pose a hazard to people are important for plants which have adapted to make use of the entirety of the solar spectrum that reaches Earth. This even includes green light which is a major source of photosynthesis despite the peak photosynthetic response of chlorophyll a and being in the blue-violet and red-orange nanometer ranges. The green color of leaves serves less to reflect green light and more to allow it to be transmitted through the leaves reaching much further into the canopy than other colors of light with the exception of Far Red.

Previous light research had focused on spectrum of peak absorption for chlorophyll a and b. This resulted in misconceptions about artificial lighting and there are numerous examples of lamps on market that contains mainly blue and red frequencies of light. The light from these lamps tends to be a reddish purple. It turns out that these types of so called grow lights are based on outdated and inaccurate information about photosynthesis. A bright white looking light source with plenty of visible bright lumens in the green spectrum is actually superior to the purple grow lights.

It is a common misconception that the frequencies of light that appear bright to the human eye are not ideal for growing plants and the same basic misconception claims that brightness lumens are a poor measure of the quality of lamps rich in red and blue frequencies because the lamps specialize in PAR output or Photosyntheticaly Active Radiation. Unfortunately the truth is that the same frequencies of light that are perceived as bright to the human eye are also those frequencies of high energy photons that that penetrate through the upper leaves and reach the lower leaves and they produce a very large amount of photosynthesis.

The light from lamps producing reddish purple light doesn't penetrate very far through leaves of the plant canopy and that means that the majority of the leaves of a plant with a canopy are not harvesting photons for photosynthesis despite both evolution making most leaves green to allow green light to penetrate through the top leaves so it can reach the majority of the photosynthetic tissue and despite the primary purpose of a leaf being photosynthesis itself.

Using mainly red and blue light decreases the total amount of plant material that can actively harvest photons because red and blue penetrate poorly through the canopy. Growth of plants is a result of photon harvest in photosynthesis and having more leaves photosynthesizing results in more energy for growth. Using grow lights with purplish color red and blue combined light frequencies results in reduced plant growth and development when compared to light sources that can reach more leaves resulting in a higher total photon harvest capacity per plant per day.

Lights that appear brighter to the human eye due to higher values of brightness lumens are actually superior to the reddish purple light of grow lights and I have repeatedly observed this over the years.

About 22 years ago in the late 90s I purchased a two tube four foot long 80 watt shop light fixture and 2 40 watt 4 foot long fluorescent grow bulbs that produced a pinkish purple light. This light was mostly in the red and blue frequencies that primitive chlorophyll studies indicated was specifically Photosynthetically Active Radiation (PAR).

After months of using these bulbs I read an interesting claim that bulbs which look brighter were superior to the purple grow lights because basically brighter means more light and more light means more and faster growth to a point.

So I bought new 4 foot fluorescent tubes... with one being warm white the other being cool white. Each of these tubes produced about 4000 brightness lumens and within a week the difference in growth was so profound that it was hard to believe without seeing it first hand. The so called grow lights were inferior for growing plants when compared to lights designed for residential use and at the time I thought that this was because the residential lights were brighter and produced more light overall. After all more light equates to more photons and more photons equates to more available energy for photosynthesis.

However with the new information that has recently become available I now realize that the increased growth from the residential types of bulbs isn't only a result of the lights being brighter. The residential fluorescent lights also produced more green light which reached more leaves and promoted more photosynthesis. For the record yes I was mostly growing Cannabis at the time and it was illegal to do so. I have not grown Cannabis since 2013 and at that time I was legally growing medical Cannabis in California. I have not illegally grown Cannabis for more than 20 years.

It is a myth that lights appearing brighter to people because they have more green in them are poor choices for plant growth. It is also a myth that plants cannot make good use of the frequencies of light that appear brighter to the human eye. Another related myth is the notion that although reddish purple grow lights appear dimmer to the eye they are actually more efficient for photosynthesis because they provide light in the exact or precise frequencies that plants use.

Plants on this planet are adapted to sunlight and leaves are green to allow green frequency photons to penetrate through them and reach even more leaves that can make use of them thus increasing the total amount of photosynthesis a plant can perform.

High PAR grow lights that cast reddish purple tinted light are nothing more than a gimmick and don't actually produce more growth, faster growth or higher quality growth when compared with lights of the same equivalent watt value that produce light that in comparison to the grow bulbs appears to be brighter and whiter to the human eye. Brightness lumens ratings matter and a bulb that producing more lumens is going to be superior for plant growth in comparison to a bulb that produces less lumens regardless of the frequencies it provides light in.

For more information about spectral quality and plant response I suggest watching the following educational videos.

Despite the majority of the videos being oriented towards Cannabis growers they contain recent and accurate information about lighting and photosynthesis and that information is applicable to nearly all vascular plants including Capsicum.





 
Dr. Bugbee is one smart dude. 
 
Do they have smaller CMH set-ups that could run at potentially less heat output? I've always been interested in growing with them.
I never quite understood all the targeted spectrum stuff. Maybe I'm just simple minded, but I always thought we're just trying to recreate the sun with our light set-ups.
 
Spot on except for this part- physics dictates that the colors we see are actually reflected and the rest are absorbed- green frequency photons are bouncing off the leaves.
 
Also, there are dimmable 315's that could help with mitigating brightness issues, and folks in florida use shade cloths- would be a simple mechanical fix for allowing the full spectrum penetration since mylar doesn't allow specific wavelengths through.
 
Nice post man!
 
Max Nihil said:
Plants on this planet are adapted to sunlight and leaves are green to allow green frequency photons to penetrate through them and reach even more leaves that can make use of them thus increasing the total amount of photosynthesis a plant can perform.

 
 
Demented said:
Dr. Bugbee is one smart dude. 
 
Do they have smaller CMH set-ups that could run at potentially less heat output? I've always been interested in growing with them.
I never quite understood all the targeted spectrum stuff. Maybe I'm just simple minded, but I always thought we're just trying to recreate the sun with our light set-ups.
I am not aware of any CMH of a lower wattage than 315. There are some extremely good Chip On Board (COB) LED lights in lower wattage than 315. A 10 watt COB can produce as many as 5000 lumens and COB lights can be found in 5000k color temperatures with a CRI of 90 although the CRI value is usually lower. They can also be found in other Kelvin color temperatures like 3500k. A 54W 3500k with a CRI of 80 and an output of between 11,000 and 12,000 lumens. You can find them with a 10 year warranty for about $130.

Cree COB CXB-3590 comes in a range of color temps and forms the basis of many excellent grow lights that for all intents and purposes compare well to CMH/LEC options. The COB lights produce more lumens per watt than the LEC but tend to have a lower Color Rendition Index (CRI) than the LEC, which is closer to sunlight.

These CXB-3590 COB LEDs have a wide spectral output that starts around 400 nanometers and ends near 800 nanometers. This unfortunately means they have zero UV (<400nm) output but they do provide Far Red (>700nm <740nm)

While the spectrum of these LEDs is not as nice as that of LECs the high lumens per watt efficiency means more light for the same amount of energy so a 54 watt Cree COB with 11,000 lumens is nearly 3 times brighter than a 50W metal halide!

On that note I just learned something.
Here is a link:
https://ilighting.com/products/ge-42069-constantcolor-cmh-ceramic-metal-halide-cmh39upar20sp10-39-watt-lamp.html

Evidently there are Ceramic Metal Halide lamps that use less than 315 watts. The link shows a 39 watt bulb in the $60 dollar range. It has a color temp of 3000, a CRI of 84 and a lumen output of 2100. The glass lamp lens will reduce the amount of UV light emitted which is probably why the CRI is only 84. The spec PDF warns that if the outer glass is damaged the bulb can cause serious UV burns and the lumens per watt is 54.

A 315W LEC grow light usually produces more than 100 lumens per watt and many bulbs have a CRI above 97! (Sunlight = 100 CRI and the closer the CRI value to 100 the more sun-like the light is.)

I don't think that these smaller CMH lamps are particularly promising but they do exist.

I was mistaken about the lumen output of the 4 foot 40 watt fluorescent tubes I ended up using around 1998. The output of one residential tube was just over 2000 lumens and the two tubes in a fixture emitted about 4500 lumens while the grow lights were more like 3000 lumens for both tubes together. Sorry about that. I was rather tired when I wrote that and was mistaken.

I think that for growers who want smaller wattage lamps the best option is to go with the COB LEDs. The smaller an HID lamp is and the lower it's wattage the less efficient it tends to be. Because of this a 54 watt COB LED puts a 50 watt Metal Halide to shame.

You might consider a CANAGROW 300W Full Spectrum COB LED Grow Light. Like so many lights today the wattage size listed of 300 is a lie. The light uses 40 watts. The manufacturer writes 300W because they claim that this 40 watt light puts out the same amount of lumens that a 300w HID does. However a 300w HID fixture can produce from 24,000 lumens up to around 36,000 lumens. The 40w COB LED produces 5000 lumens. You would need 5-7 of the LEDs to actually produce the same amount of light that the HID fixture does.

The COB LED lamp is rated at 100,000 hours of life and many HID ballasts have a lifespan around 50,000 hours. A nice 315 watt CMH ballast costs around $130 to $150. The COB LED equivalent of 5-7 lamps runs between $300 and $500. It turns out that the price of the HID systems is less than the price of equivalent COB LED lighting even when parts are replaced over 100,000 hours of use.

The efficiency of the COB LEDs is actually not particularly impressive and is generally comparable to that of 250-315W HID systems. The CRI of some CMH bulbs is above 97 and many are above 90. The CRI of the COB LEDs tends to be around 80 and some even go up to about 90 but the CRI of CMH lamps tends to be considerably better than that of equivalent wattage of LED lighting.

The COB LEDs generally do produce Far Red light but produce little to no UV light.

Basically COB LEDs can compare to CMH LEC in some ways but still aren't a match for them in general for quality of light, brightness, price and long term operating cost.

It is true that some high end LED fixtures do produce many more lumens per watt than equivalent wattage HID lights do but there is a catch. The LED light systems that are more efficient at producing light do not produce a continuous high CRI spectrum of light. Instead they tend to produce blue and red lights correlating to the old information about chlorophyll peak reaction spectrum. So sure the LEDs produce more light but it is light that cannot even penetrate through the canopy and reach lower leaves. Because of this many LED growers are experimenting with additional supplemental sources of light below or to the side of the canopy as that their high efficiency light is wasted in the upper canopy where a minority of a plants total chlorophyll is and that chlorophyll can only harvest so many photons. Unused photons end up being absorbed by the upper leaves and because they fail to penetrate through the leaves they never end up being a source of energy.

What is the point of being able to produce 4 times as many lumens per watt when it is in a spectrum that can only reach a small amount of a plants total chlorophyll? The high light production efficiency is offset by the strongly decreased photosynthetic efficiency for the entire plant.

There is a reason that CMH lights are the preferred lighting of Cannabis growers and it isn't just because the UV component of the light results in much more potent product than other forms of lighting.

In terms of a 40w lamp a $70 COB LED is not a bad option but when it comes to higher wattage and stronger light requirements with high CRI full spectrum lighting LED lights in general just don't compete with CMH... yet.

There is another form of lamp that I suspect may hold promise for the future of horticultural lighting. However the technology is still rather new and to the best of my knowledge has yet to be applied towards making grow lights. I am talking about laser based lighting of the type that is currently used for the headlights of the Rolls Royce Phantom VIII. Seriously check it out.

The laser headlights were not designed for horticultural applications but instead were desired to put bright beams of high intensity light where a driver is looking. The lights are efficient and though laser based they are not bright enough to damage human vision. The beams of light nevertheless project considerable distance with little change in photointensity. This is entirely unlike most horticultural lights whose light intensity rapidly decreases as it moves further the bulb.

Despite their widespread use in horticultural lighting ceramic metal halide lights were not invented or designed for use as grow lights. They were intended as show lights used to produce efficient bright light very similar to to sunlight. Such lights show colors as true to how they look in sunlight unlike most other forms of lighting which alter color rendition due to the low Color Rendition Index (CRI) values. Incandescent lighting make things look more yellow and HPS lighting make things more pink, orange and yellow... Metal Halide lighting makes things look more blue white... but Ceramic Metal Halide lighting makes things look more like themselves because objects illuminated with CMH look like they do in actual sunlight and when it comes to showroom displays that matters. Similarly the laser based lighting developed for RR Phantom VIII may hold promises as the foundation of a whole new type of horticultural lighting that could potentially replace not only HID lights but LED lights as well.

The future of lighting is looking kinda bright.

For now though I am going to stick with my 315 watt LEC.

[/\/\][/\/]
 
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Yumyumyellow said:
Spot on except for this part- physics dictates that the colors we see are actually reflected and the rest are absorbed- green frequency photons are bouncing off the leaves.
You aren't wrong however green light photons have been shown to penetrate through leaves and personally I find the green tinted filtered light beneath the canopies of certain trees to be quite pleasant. Certainly a percentage of the green light that reaches leaves is reflected but it usually is not a large percentage if I am not mistaken. So green light both passes through leaves as well as reflects from them and both of these aspects are factors in it's ability to penetrate plant canopies.

To me it is like tinted glass, if you look at colored class the glass looks colored because it reflects that color of light however if you look through tinted glass the world looks colored because the glass also transmits that color of light.

Unless I am mistaken and if that is the case I welcome any correction.
 
Max Nihil said:
I am not aware of any CMH of a lower wattage than 315. There are some extremely good Chip On Board (COB) LED lights in lower wattage than 315. A 10 watt COB can produce as many as 5000 lumens and COB lights can be found in 5000k color temperatures with a CRI of 90 although the CRI value is usually lower. They can also be found in other Kelvin color temperatures like 3500k. A 54W 3500k with a CRI of 80 and an output of between 11,000 and 12,000 lumens. You can find them with a 10 year warranty for about $130.

Cree COB CXB-3590 comes in a range of color temps and forms the basis of many excellent grow lights that for all intents and purposes compare well to CMH/LEC options. The COB lights produce more lumens per watt than the LEC but tend to have a lower Color Rendition Index (CRI) than the LEC, which is closer to sunlight.

These CXB-3590 COB LEDs have a wide spectral output that starts around 400 nanometers and ends near 800 nanometers. This unfortunately means they have zero UV (<400nm) output but they do provide Far Red (>700nm <740nm)

While the spectrum of these LEDs is not as nice as that of LECs the high lumens per watt efficiency means more light for the same amount of energy so a 54 watt Cree COB with 11,000 lumens is nearly 3 times brighter than a 50W metal halide!

On that note I just learned something.
Here is a link:
https://ilighting.com/products/ge-42069-constantcolor-cmh-ceramic-metal-halide-cmh39upar20sp10-39-watt-lamp.html

Evidently there are Ceramic Metal Halide lamps that use less than 315 watts. The link shows a 39 watt bulb in the $60 dollar range. It has a color temp of 3000, a CRI of 84 and a lumen output of 2100. The glass lamp lens will reduce the amount of UV light emitted which is probably why the CRI is only 84. The spec PDF warns that if the outer glass is damaged the bulb can cause serious UV burns and the lumens per watt is 54.

A 315W LEC grow light usually produces more than 100 lumens per watt and many bulbs have a CRI above 97! (Sunlight = 100 CRI and the closer the CRI value to 100 the more sun-like the light is.)

I don't think that these smaller CMH lamps are particularly promising but they do exist.

I was mistaken about the lumen output of the 4 foot 40 watt fluorescent tubes I ended up using around 1998. The output of one residential tube was just over 2000 lumens and the two tubes in a fixture emitted about 4500 lumens while the grow lights were more like 3000 lumens for both tubes together. Sorry about that. I was rather tired when I wrote that and was mistaken.

I think that for growers who want smaller wattage lamps the best option is to go with the COB LEDs. The smaller an HID lamp is and the lower it's wattage the less efficient it tends to be. Because of this a 54 watt COB LED puts a 50 watt Metal Halide to shame.

You might consider a CANAGROW 300W Full Spectrum COB LED Grow Light. Like so many lights today the wattage size listed of 300 is a lie. The light uses 40 watts. The manufacturer writes 300W because they claim that this 40 watt light puts out the same amount of lumens that a 300w HID does. However a 300w HID fixture can produce from 24,000 lumens up to around 36,000 lumens. The 40w COB LED produces 5000 lumens. You would need 5-7 of the LEDs to actually produce the same amount of light that the HID fixture does.

The COB LED lamp is rated at 100,000 hours of life and many HID ballasts have a lifespan around 50,000 hours. A nice 315 watt CMH ballast costs around $130 to $150. The COB LED equivalent of 5-7 lamps runs between $300 and $500. It turns out that the price of the HID systems is less than the price of equivalent COB LED lighting even when parts are replaced over 100,000 hours of use.

The efficiency of the COB LEDs is actually not particularly impressive and is generally comparable to that of 250-315W HID systems. The CRI of some CMH bulbs is above 97 and many are above 90. The CRI of the COB LEDs tends to be around 80 and some even go up to about 90 but the CRI of CMH lamps tends to be considerably better than that of equivalent wattage of LED lighting.

The COB LEDs generally do produce Far Red light but produce little to no UV light.

Basically COB LEDs can compare to CMH LEC in some ways but still aren't a match for them in general for quality of light, brightness, price and long term operating cost.

It is true that some high end LED fixtures do produce many more lumens per watt than equivalent wattage HID lights do but there is a catch. The LED light systems that are more efficient at producing light do not produce a continuous high CRI spectrum of light. Instead they tend to produce blue and red lights correlating to the old information about chlorophyll peak reaction spectrum. So sure the LEDs produce more light but it is light that cannot even penetrate through the canopy and reach lower leaves. Because of this many LED growers are experimenting with additional supplemental sources of light below or to the side of the canopy as that their high efficiency light is wasted in the upper canopy where a minority of a plants total chlorophyll is and that chlorophyll can only harvest so many photons. Unused photons end up being absorbed by the upper leaves and because they fail to penetrate through the leaves they never end up being a source of energy.

What is the point of being able to produce 4 times as many lumens per watt when it is in a spectrum that can only reach a small amount of a plants total chlorophyll? The high light production efficiency is offset by the strongly decreased photosynthetic efficiency for the entire plant.

There is a reason that CMH lights are the preferred lighting of Cannabis growers and it isn't just because the UV component of the light results in much more potent product than other forms of lighting.

In terms of a 40w lamp a $70 COB LED is not a bad option but when it comes to higher wattage and stronger light requirements with high CRI full spectrum lighting LED lights in general just don't compete with CMH... yet.

There is another form of lamp that I suspect may hold promise for the future of horticultural lighting. However the technology is still rather new and to the best of my knowledge has yet to be applied towards making grow lights. I am talking about laser based lighting of the type that is currently used for the headlights of the Rolls Royce Phantom VIII. Seriously check it out.

The laser headlights were not designed for horticultural applications but instead were desired to put bright beams of high intensity light where a driver is looking. The lights are efficient and though laser based they are not bright enough to damage human vision. The beams of light nevertheless project considerable distance with little change in photointensity. This is entirely unlike most horticultural lights whose light intensity rapidly decreases as it moves further the bulb.

Despite their widespread use in horticultural lighting ceramic metal halide lights were not invented or designed for use as grow lights. They were intended as show lights used to produce efficient bright light very similar to to sunlight. Such lights show colors as true to how they look in sunlight unlike most other forms of lighting which alter color rendition due to the low Color Rendition Index (CRI) values. Incandescent lighting make things look more yellow and HPS lighting make things more pink, orange and yellow... Metal Halide lighting makes things look more blue white... but Ceramic Metal Halide lighting makes things look more like themselves because objects illuminated with CMH look like they do in actual sunlight and when it comes to showroom displays that matters. Similarly the laser based lighting developed for RR Phantom VIII may hold promises as the foundation of a whole new type of horticultural lighting that could potentially replace not only HID lights but LED lights as well.

The future of lighting is looking kinda bright.

For now though I am going to stick with my 315 watt LEC.

[/\/\][/\/]
I'll have a better read through this later, but I'm still not on board with LED's.
It's silly and possibly flawed logic, but shop lights, cheaper CFL's, metal vapor bulbs, and the sun all set off my auto-darkening welding hood. LED grow lights on the other hand, not even a flicker. So there's definitely way more light coming from the other bulbs, and it takes UV and IR to trigger my hood darkening.
 
I keep forgetting to mention the photoschedule I am using for the indoor grow box.

The 24 hour period is broken up into 3 sets of 5 hours on and 3 hours off for a total of 15 hours of light and 9 hours of dark.

It is experimental to some degree but I have read that the duration of light and dark periods doesn't have much impact with Capsicum and they can even grow with constant light 24/7.

I figure that 15 hours of light in a day is plenty but rather than it being all at once I decided to space it out in even increments. It also helps prevent the larger temperature swings that can occur when a light stays on 15 hours in a row in a closed room.
 
Thanks for the link on those smaller CMH bulbs. I'll have to look into that more. I'm going super budget with a couple of overseas special 2ft T5's with mixed 3000k and 6500k bulbs in hopes of more light radiation.
 
What you're saying about LED's backs up what I was feeling about them.
 
I've been wanting to test the effects of welding arc on growing peppers. Possibly leaving one on my tool box for a month and seeing how it grows in comparison to one at home. It's basically just a 57.5KW incandescent bulb in my band. 
 
With your light cycle test, what species are you growing? Have you noticed different species prefer different amounts of light? 
 
Demented said:
 
With your light cycle test, what species are you growing? Have you noticed different species prefer different amounts of light?
That smaller CMH bulb and wattage is not particularly efficient and the specs for COB LEDs of similar wattage are considerably better.

While in comparison to CMH lights LEDs just don't produce the same results that doesn't mean that LED lighting cannot grow healthy plants. Ironically using many bright white LED bulbs in a grow will tend to outperform an equivalent wattage of LED grow lights. I used around 20 5000k 18W LED bulbs at 60w/sq' the other year to grow cacti and the results were unbelievably good. However it is true that I know the people who own the company that makes them and they didn't cost me anything. However the setup would have been nearly $300.

I ended up putting those bulbs in fixtures around the house and purchased a CMH grow light.

With the set-up I depict in the initial post it has only been operating for a few days now.
I do have a tray of open pollinated Echinocereus triglochidiatus var inermis seedlings in the growing unit but everything else in there is Capsicum and in the annuum/frutescens/chinense complex. I have about two dozen different types growing in there.

In the few days that they have been under the light with the aforementioned light cycle I HAVE observed the seedlings to be growing rapidly but they also a constant supply of 20:20:20 fertilizer mixed into the water I water them with. I use about 1/3 of a teaspoon of the fert per gallon of water and I are about a half a teaspoon of citric acid with it as well. I am using tap water and here it is rather hard, has a pH generally between 7.5 and 8 and has several mineral salts dissolved in it like calcium and magnesium.

One of the most valuable tools I have for growing plants indoors is a gallon pump sprayer and I use this to deliver the water and fertilizer mixture to the plants. I have a large number of houseplants and I do the same with them as well.

So far the Capsicum are growing well but honestly most varieties of are very easy to grow. I certainly don't grow them for the challenge of it.

Honestly I am of the opinion that LED lighting holds tremendous promise as a technology that is undergoing development and it has provided me with good results in the past when I used residential type bulbs. I use 5000k LED lighting on several of my fish tanks and I use them to start seeds as well. They are useful. I have observed them to frequently burn out though and that includes every brand I have tried. I bought 2 5000k 150W waterproof outdoor flood lights online awhile ago for a fish tank and they worked extremely well for the 4 months they lasted before they burned out just like almost every LED I've used so far. I do have a 170W high bay 5000K fixture from a home improvement store that has been running about a year though. However when I tried using it to grow cacti it wasn't bright enough to give me the results I wanted. It replaced the flood lights on the aquarium when they burned out. It would be effective for Capsicum but there are better and more affordable LED options out there.

I recently tried a Brinks 40 watt 5000k LED security bulb. I bought it at WLMRT for $20 and it is okay with damp locations, has 4800 initial lumens and the manufacturer claims it will last 22 years. For me it lasted 3 months at most at 8 hours a day. It does however have a limited lifetime warranty and I kept the box. It works well enough but like so many products the actual lifespan is nowhere near the claimed lifespan.

A friend who works at a home improvement store informed me that the store actually keeps track of how long it takes for the store display lights to fail and evidently none of them last anywhere near the amount of time claimed by the manufacturer, which incidentally is owned by the same company as the store itself. They actually know that the product information about lifespan is not even close to accurate and the employees don't consider most of the lights to actually be worth buying but you will never hear that in the store. Selling is about money, not honesty.
 
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