Those growers that have grown a crop or two know firsthand that the stronger the light source the better the green. This usually meant that either metal halide or high-pressure sodium lamps (or both) were going to be used to grow the plants. The most common wattages for both types of lamps are 240, 400 or 1000 watts. These high-intensity discharge lamps have been the mainstay of cannabis growers for decades. Some would say they were simply the only viable options.
Fluorescent lighting was found to be a shoo-in for sprouting seeds or rooting clones, but was unable to provide enough light to fuel the plant during its foliage growth period and, later on, the budding/flowering stage. Lights of this type are inadequate when it comes to intensity with common power ratings of only 20 or 40 watts.
Mercury Vapor (MV) lamps are a great light source for early foliage growth but they emit so much heat that it quickly becomes apparent that supplemental cooling will be needed, and lots of it! Mercury Vapor is also a very inefficient technology and should not really be employed unless the growing environment is already too cool. An MV lamp or two will increase the temperature of the growing environment by a few degrees and also shower the foliage with another useful source of light.
Lighting technology has matured over time resulting in the emergence of a few really interesting and ingenious sources of artificial light. There are three lighting options that could be the answer to the problem of practical, low cost and scalable artificial lighting systems. These three are:
- The Light Emitting Diode
- The Sulphur Lamp
- The Magnetic Induction Lamp
These three technologies represent the next generation of indoor illumination solutions. Each has its own pros and cons and each is pretty amazing. In this discussion I will present these pros and cons and let you decide whether to invest in a closer look.
The Light Emitting Diode (LED)
Light Emitting Diode (LED) technology in the grow room has become widespread with most growers utilizing it on a daily basis. LEDs are bright, use little energy and produce little heat. But did you know you can use them as grow lights? There are many companies that specialize in LEDs and many of them offer custom sheets of LEDs.
By utilizing LED technology to grow your crop you will achieve some welcome and surprising results. LED sheets are the way to go if you have your operation in something such as a walk-in closet or a basement. The entire setup is so lightweight that you can stack your growing areas on top of each other. Very cool (literally)! LEDs are a mature technology and are now a viable option for your artificial lighting needs.
Sheets of LEDs can be of any size or shape but for practical purposes, you want a uniform shape. A sheet of LEDs with dimensions of 2 x 4 feet will easily output 5,200 lumens of light and a growing closet lined with ten 2 x 4 LED sheets will output an amazing light show of 52,000 lumens!
Traditional single source lamps such as metal halides have always had the problem of scorching the tops of our favorite green. These lights produce high heat and the light source is from only one direction leaving the lower branches of your plants to be light starved and phototropic. LED sheet lighting is the solution to these problems.
By placing the light source in a 360-degree (vertical and horizontal) arrangement you will be able to distribute light to all sections of the plants resulting in vigorous growth and some couch glue grass after harvest.
Each panel requires only 60 watts of power to start. With ten LED sheets lighting the grow area this means your lighting requirements will be only 600 watts. The heat generated by one of these sheets is negligible. With a fairly light electrical load, you will be able to position your LED sheets in places you had previously found impossible.
Some LED manufacturers also offer tuning modules that vary the frequency of light the LEDs are emitting. In laymen’s terms, this means you can change the color of the light your sheet is emitting. This ability to dial up any single color (light spectral frequency) is a boon for growers, as cannabis likes a blue/white light during its foliage growth phase and shifting to a more orange light to support maximum flowering and budding.
Most growers use a metal halide lamp for the green foliage growth stage and change to a high-pressure sodium lamp for the flowering/budding stage. With the light-changing ability of LEDs you won’t have to change out your grow lights for each growing phase.
The setup of LED sheets is simple as they are lightweight and made of tough materials. Mounting to a simple wood frame is the easiest way to set up your grow area. Because these sheets are so lightweight you don’t have to worry about using heavy-duty mounting hardware to support the heavy ballast transformer that both metal halide and high-pressure sodium lamps require.
The Sulphur Lamp
The Sulphur Lamp (SL) was invented in 1990 and offers efficiency almost rivaling high-intensity discharge (HID) lamps. With an output of 100 lumens per watt, the sulphur lamp exceeds the output of more commonly used HID systems. Sulphur lamp wattages typically start at 1000 watts (commonly metal halide and HPS lamps are in this same wattage range).
The SL bulb works by exciting sulphur with microwaves in the 510-nanometer wavelength with 73 percent of the emitted light being in the visible range. The remaining emitted light is in the near-infrared wavelengths resulting in a light with a slightly greenish hue.
Early SL bulb models (which you may still encounter) required a cooling fan but this has been eliminated by using a spiral guide within the microwave emitter and bulb that agitated the resulting sulphur plasma eliminating the hot spots that were the bane of earlier SL models. This innovation also eliminated the need for a motor that constantly rotated the bulb to eliminate these hot spots.
The SL is not confined only to a traditional bulb shape. Light pipes are possible which can be up to 40 meters (130 feet) in length. Shorter light pipes require only one microwave emitter at one end and a mirror at the other end. Longer pipes require a microwave emitter at both ends of the pipe.
The National Air & Space Museum installed three 27 meter SL light pipes to replace 94 HID lamps which increased the amount of available light. Combined with a lifespan of 60,000 hours per lamp this switch from HID bulbs to SL pipes was also an economical choice.
Sulphur lamp lighting technology is relatively new and has been slow to catch on. Despite the obvious benefits, SL heat generation and the problem of emitted high-energy microwaves have slowed the proliferation of sulphur lamps.
A newer model of SL presently under development does not use a microwave emitter. Rather, it uses two electrodes in the same configuration as HID lamps. This innovation, if proven successful, will eliminate the microwave emitter and remove a key barrier to widespread commercial usage of the sulphur lamp.
In the future, expect to see sulphur lamps lighting large areas such as stadiums or airplane hangars. As SL usage rises associated costs will inevitably come down. The SL is still in its infancy. In years to come, it is expected that sulphur-based lighting will become a mainstay of high-intensity lighting. Stay tuned!
The Magnetic Induction Lamp
There is another less-used but very effective alternative lighting source; the Magnetic Induction Lamp (MIL). The main difference between the MIL and other lamps is the fact that there are no electrodes within the bulb. MILs still use a ballast to step up the 120 volts taken from the wall socket to the higher voltage needed to light the gas within the bulb. The use of electrodes within the bulb are usually the limiting factor of the bulb’s lifespan since the electrodes degrade quickly. Most lamps that use an electrode filament have a working life in the range of 15,000 to 50,000 hours. In contrast, MILs have a working life of about 100,000 hours or up to 11 years of continuous operation. This amounts to a 50 percent savings in energy costs for the same amount of light generated.
The MIL will generate 90 lumens per watt of power making it a very good choice for growing applications. While it still uses a small ballast, the unit as a whole is lighter in the lower ranges of power usage than a traditional lamp such as a metal halide. A 400-watt MIL will output 36,000 lumens of light, which is the same amount of light that a 400-watt metal halide lamp will produce. The savings result from the significantly longer lifespan of the MIL.
Magnetic induction lamps do not have a “heating up” phase that the more commonly used bulbs have. The MIL bulb emits light almost instantaneously and can be relit as many times as needed in a short amount of time. The metal halide bulb, in contrast, takes several minutes to light completely.
Magnetic induction lamps typically operate between 100 and 300 volts. Those used within a common household setting in North America are optimized for a 120 volt/ 60hertz power source.
One disadvantage of using a MIL is the radio frequency (RF) “noise” that is produced. This noise commonly interferes with electronic communication devices such as cellphones and wireless wi-fi access. Newer MIL bulbs have shielding that helps reduce the affected area and thus comply with most local governmental RF noise pollution regulations. Another disadvantage is the fact that the bulb number and ballast size grow exponentially as you increase the wattage of the lamp. The lamps and ballast quickly become ungainly and take up more space than traditional bulbs such as metal halide and high-pressure sodium.
While the MIL is still a no-go for most growers it is still a viable light source for a grow room. At 400 watts the light generated is almost pure white. There is very little heat generated compared to other lighting systems and it is a “hard-to-break” technology; the bulbs are very sturdy and last forever. The acoustic noise generated by the ballast is also absent so the system will be completely silent.
Since the MIL is not presently in widespread use in the hydroponics world the cost of a full system is still more expensive than metal halide or high-pressure sodium systems. The long-term cost savings are high but most home growing operations usually operate for only 8 to 10 weeks at a time negating the main advantage of using the MIL.
The bottom line
No matter what lighting solution is finally chosen being aware of the latest available technology can stimulate personal experimentation. I suggest starting with a walk-in closet walled with LCDs of varying intensity and color. It is the coolest (and brightest) choice!