CMH Grow Lights vs HPS Grow Lights
Growing plants indoors poses all kinds of problems, but thankfully, modern technology has the solutions that readers are looking for. Arguably the best of these available on today's markets is the ceramic metal halide, or CMH grow light. Whether readers are looking into indoor growing for the first time or they're just looking to upgrade from less efficient and less effective lights, they can read on to find out about a few of the advantages of investing in this impressive, thoroughly modern technology.
What is CMH grow lights?
The crux of the matter; what are LEC lights and why are they sometimes called ceramic metal halide (CMH) or ceramic discharge metal halide (CDM)? Thankfully, all terms mean the same thing, and as awareness of the technology increases, these terms are becoming interchangeable. An LEC light uses a ceramic arc tube, rather than the quartz version found in regular MH lights. The result is a more natural colour, producing more lumens per watt and lasting a lot longer. The most common model of LEC fixture is the 315W with a “4200K” colour bulb.
Advantages of CMH
Spectrum
The CMH spectrum combines the red-heavy HPS spectrum with the blue-heavy MH spectrum in one bulb, making it the perfect light for all stages of growth. With a high CRI, it is extremely close to natural sunlight, which is great for your plants and for your eyes (plants look more natural, making it easier to spot any discolorations or other issues).
Efficiency
CMH bulbs give you a much higher PAR output (the amount of light that is usable by plants) per watt than any other type of lighting, apart from the most expensive LED grow lights.
Color Rendering Index
They also have a more natural CRI (Color Rendering Index). CRI describes how the color of a light source changes how an object appears to the human eyes and how well subtle variations in color shades are revealed. The higher the CRI, the more realistic things look. CMH grow lights are generally rated between 80 to 96 CRI, by comparison, the sun is rated at 100 CRI. This means that CMH grow lights will let you see the true color of your plants without making your grow room look yellow, blue or purple.
Ultraviolet Radiation
CMH grow lights provide UV (ultra violet) radiation, which although being outside of our range of vision is beneficial (at certain ranges and intensities) to plant growth and development. They produce UV-A, UV-B and UV-C Light, but UV-C is generally very harmful to human eyes. So most high quality manufacturers use a glass filter to block the UV-C output while leaving UV-A and UV-B output intact.
Cost Is Falling
Ceramic metal halide bulbs are not the cheapest way to go for grow light options. In fact, they cost many times more than other types. As they continue to take a larger part of the market share of grow lighting, their cost is beginning to come down. As CMH bulbs are being produced in greater and greater quantities, their prices should continue to fall.
Disadvantages of CMH
No lighting solution is perfect, and LEC does carry some disadvantages. The UV-B rays given off are harmful to humans. Adequate safety equipment is needed to reduce any risks to your skin or eyes. At present, the high setup costs of LEC can be off-putting. Because the technology is newer, they cost a lot more than traditional bulbs like CFLs, although this attribute is somewhat of a double-edged sword. The initial cost is higher, but the long-term running costs sit somewhere between HPS and LED bulbs.
They also give off a lot of heat. It is less than HPS or MH lights, but enough to warrant sufficient airflow and cooling options, again potentially adding to the startup cost if you do not already own ventilation equipment. Another consideration would be the positioning of LEC lights versus an HPS grow light. LECs don’t quite match the same light intensity of HPS varieties, so you would need to position the fixture closer to the canopy of your cannabis crop. Lastly, glass blocks UV-B rays given off by LEC bulbs. Growers would need to rethink any obstructions between the lights and plants.
High Intensity Discharge Grow Lights
High intensity discharge lights, or HIDs, are large-bulbed systems that create light by igniting a gas inside the bulb. HIDs are available in two types: Metal halides (MH) and high pressure sodium (HPS). There is a third type, which is a hybrid between the two, as well. All types of HIDs work by arcing an electric current between two tungsten (W) electrodes which then ignites the gas in each particular bulb.
Metal halide lamps burn gas that produces lighting on the blue end of the spectrum which is beneficial during the vegetative phase of a plant’s development. High pressure sodium lamps produce light on the red to orange portion of the spectrum and are useful during the flowering stage of a plant’s cycle.
Pros of HPS Grow Lights
HPS knobs are always dimmable, which can be ideal to modify the measure of required light for a given area.
If utilizing a digital ballast, a wide range of HPS grow lights can be utilized without changing the ballast.
Cons of HPS Grow Lights
HID knobs heat up consistently and this can burn plants if not observed or taken proper care of when you put them into a grow room.
They require extra equipment to work, for example, a reflector and a ballast. Some HID ballast will just work HPS and some will just work MH, which means several ballasts might be needed.
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