Indoor plant growers take on a lot of responsibility. Starting from deciding what kind of crop to grow to deciding where and how to grow it.
The improvement in technology, nowadays, has facilitated this process greatly. The lights used to grow the plants have evolved to become more efficient and more productive than ever.
The varieties available on the market include metal halide (MH), high-pressure sodium (HPS), light-emitting diode (LED) and finally the ceramic metal halide (CMH).
We’ll be discussing the latter in more detail below, along with its benefits and drawbacks. We’ll also be listing some of the best CMH grow lights available in 2019.
Top 5 Best CMH Grow Lights Comparison Chart
Reviews of the 5 Best CMH Grow Lights
We’ll help you narrow your choices of CMH grow lights by listing some of the best choices available in the market.
Grow Co. is known among consumers to be one of the trusted brands in the market, that produce high-quality grow lights, which will keep your crops as healthy as can be.
It comes in a size of 20x12.5x12 inches with a weight of 12.05 pounds and uses the 315 Watt Philips Master Color 3100K lamp, which is known for having high strength, stability, and a full spectrum.
They also sell a version that operates using 630 Watts of power, which holds 2 lamps and produces double the light intensity.
The best thing about these grow lights is that the heat emissions are low, thus preventing the crop from catching fire.
It also has a reflector made from high-reflective hammer tone aluminum, but the producers don’t really include the exact amount of reflectivity that you get.
The square wave ballast of the system comes with a ballast housing that’s fully sealed, which produces a low frequency to prevent electromagnetic interference.
The downsides of such a strong bulb are that it’s really bright, so you’ll need to wear protection glasses and that the ballast is external, which decreases the appeal of the system and makes it look bulkier.
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This is the CMH grow lights system that’s considered the best option in the market in 2019.
Although they’re a little costlier than other brands, with more detailed specifications, you’ll come to realize why that is.
The ballast is placed internally within the all-in-one hood reflector and it’s a square wave, electronic ballast with w low frequency (50/60 Hz), which means no electromagnetic interference will happen. It has a lifespan of 50,000 hours.
On the inside, the hood reflector is made of 98% reflective German aluminum with 95% reflective textured corners. This leads to a higher light output, maximum coverage of 4 by 4 feet, and no creation of hot spots that can burn your crops.
This system produces low heat emission from the arc tube due to its open construction, which means it’s much cooler compared to HPS or MH light systems.
However, it’s still advisable to place the kit at a height of 18 inches or more above the canopy to avoid plant burning.
It uses the same Philips bulb as the Grow Co. system, which has a long lifespan (20,000 hours), at which it still retains 85% of its PPF output and also retains 80% of its lumen output after 8000 hours of use.
This bulb also has a very high 1.95 PPF (photosynthetic photon flux) per second, which means it’s very efficient as it produces a high output while only consuming 315 Watts of power.
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This is a CMH grow lights system that’s made by a professional indoor plant growing manufacturer, with quality and durability that’ll last a long time and grow your plants properly.
Similar to the two previous models, this system uses a low-frequency square wave technology ballast, which stops electromagnetic interference.
Like the Sun System model, the hood of the system uses highly reflective Vega aluminum, which produces a high and even light output, providing coverage to plants in an area of 3 by 3 feet.
This will give you healthy crops and get a good yield out of your plants since it’s also suitable for both the flowering and vegetative stages of plant growth.
This light system also protects against overheating to avoid plant burning, short-circuiting, as well as the end of bulb and ignition failure.
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This is a kit ready for assembly as it comes with a reflector, a 315W ballast, lamp, 1/8 inches rope hanger, power cord, and metal hooks.
Another CMH grow light system that works perfectly for both the vegetative and flowering phases of plant growth. This is possible because it uses enhanced reds, which are required for flowering.
Its light spectrum is efficient, as it closely resembles the natural sunlight, as compared to HID (high-intensity discharge) systems. It also covers a larger area compared to other systems, 4 by 4 feet, giving you a larger, quality harvest.
The downside to this system is that its lifespan is a lot shorter than its comparable models, only 10,000 hours.
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We couldn’t conclude this article without pointing out how most of the CMH systems that we’ve mentioned above use this Philips bulb.
For a bulb that just consumes 315 watts, it gives you 33,000 lumens and for it to retain 90% of that after 8000 hours is perfect, as it ensures quality crops all the time.
Its lifespan is 20,000 hours, at which it also retains 85% of its initial, incredibly high PPF as we’ve pointed out above.
It runs much cooler than any HPS or MH grow lamp because it has an open lamp construction, which reduces radiant heat and provides you with a much cooler space.
It has a full 3100K color spectrum, perfect for vegging and flowering. The 4200K version that’s available if suitable for those who want to use it for vegging only or want a blue-light spectrum.
The other version has a lifespan of 30,000 hours.
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How do CMH Grow Lights Work?
CMH, Light Emitting Ceramic (LEC) or Ceramic Discharge Metal Halide (CDM) are all names for the same technology of grow lights. It’s considered among the top available on the market right now.
It has properties of both MH and HPS, as it operates using an arc tube made of ceramic. This is similar to that found in HPS grow lights instead of the quartz tube of the regular MH grow lights.
Compared to quartz glass, the pressure of the ceramic material of the arc tube in the CMH grow lights is much higher. This means that manufacturers are able to produce more accurate alterations on the spectrum.
Benefits of CMH Grow Lights
When it comes to their lifespan, their photosynthetically active radiation (PAR) spectrum, and their efficiency, CMH grow lights beat their competition easily.
Balanced Spectrum
As mentioned above, CMH lights are a hybrid of MH and HPS, as it combines the red-saturated spectrum of the former with the blue-saturated spectrum of the latter. That’s how it provides the light that’s optimum for all stages of plant growth.
It’s a more PAR efficient option, as the usable light spectrum falls between 400 and 700 nanometers. That’s why the more balanced light spectrum of CMH lights provides plants with the perfect photosynthesis rates, required for healthy growth.
On the other hand, MH and HPS lights consume a lot more power to produce light that can be converted into the nutrients required for plant growth.
Thus, their lifespan is much shorter than CMH lights, their PAR levels are much lower and they’re less efficient by at least 10%.
Color Rendering Index (CRI)
In our daily lives, we use different color lights that change the way our eyes see the objects around us. This isn’t of much importance when it comes to regular living, however it makes all the difference when it comes to growing plants.
That’s because you won’t be able to tell if there’s any problem with your plants if there are slight changes in color shades. Things will look more realistic with a higher CRI.
CRI is also known as how the quality of a light compares to the light quality that the sun produces. The sun is rated at 100 CRI with the CMH lights falling closely behind, between the range of 80 and 96 CRI.
The consistent color rendering of the CMH lights that extends throughout its lifespan allows you to see the actual color of your plants and how well they’re performing indoors.
Ultraviolet and Infrared Radiations
Although UV radiation can’t be seen with the human eye because it’s not within the range of light that can be perceived, it’s still a primary element for growing plants.
CMH grow lights emit various types of UV radiation, including UV-A, UV-B, and UV-C. All three types are essential for plant growth, within a specific range and intensity.
During their vegetative stages, plants require UV radiation to produce a better-quality yield with healthier and stronger branches.
It’s also beneficial for preventing pathogens like mold and mildew, as well as some pests from causing harm to your crop.
Because UV-C rays are harmful to the human eye, most high-end manufacturers add a glass filter to the bulb to block these rays, whilst allowing the two other types through.
If this filter is broken, don’t look at or work with the bulb, as the radiation has a cumulative effect and can burn.
Longer Lifespan
As CMH grow lights have ceramic arc tubes, they’re less likely to break and degrade at a lesser pace than other lights with quartz glass tubes like MH or HPS.
CMH lights preserve 80% of their original intensity up to 20,000 hours and they can last for 4,000 hours longer than that.
This is much higher than the 10,000-hour lifespan of the MH and HPS grow lights, which will have to be replaced frequently and add up to the overall cost.
No Electromagnetic Interference
A major turn off for in-home growers is the interference of some grow lights and electronic ballasts with electronics, such as mobile phones and TV signals.
That’s not considered an issue with CMH grow lights as they cause no electromagnetic interference.
Downsides of CMH Grow Lights
Although the benefits exceed the drawbacks, we still have to mention them to help you make a wiser, well-educated choice.
Weak Flowering
As CMH bulbs have a more balanced spectrum, this means that they’re not as heavy as HPS lights on the red spectrum which is required in the flowering phase of plants.
However, HPS lights lack the blue light that the CMH lights have, which makes it not the perfect option for plants in their vegetative state.
That’s why CMH grow lights are considered the best for the entire growth cycle.
High Heat Output
Since they produce radiation, CMH lights also produce a lot of heat compared to LED grow lights. That’s because a lot of the light produced is in the infrared portion of the spectrum, over 700 nanometers.
This means you’ll have to place them further above the plant beds to prevent burning.
High-quality CMH lights don’t produce too much heat compared to MH or HPS lights, but it’s still more than what the LED lights output.
High Initial Cost
CMH grow lights require a hefty initial investment, as it’s not particularly cheap. You can pay around $500 for a complete 315w CMH kit, while a high-end 400w MH or HPS grow light kit will only cost you $200.
This shows how the initial cost of a CMH light system is almost double that of the other light systems.
Note that a kit or system includes ballast, bulb, and reflector.
Over the long run, however, CMH lights will save you money, as they last a lot longer than other lights, which will have to be replaced frequently and they’re more efficient.
The technology of the CMH lights is in continuous development and the more customers are interested, the more prices will fall.
CMH Grow Lights Spectrum
As we’ve mentioned above, the MH is heavy on the blue light while HPS is heavy on the red light, which means growers will have to buy both for better yield quality.
That’s why the more balanced spectrum of the CMH lights, which combines both lights, is more suitable. However, you might have to combine it with HPS to overcome the shortage in the red light required for the flowering phase of the plant cycle.
Which Ballast to Choose for CMH Lights?
Most electronic ballasts are not compatible with CMH lights, as they produce an extremely high frequency. However, some manufacturers make high-end electronic ballasts with microprocessors that can run CMH lights smoothly.
If you’re just stepping foot into the CMH lights world, it’s recommended that you buy a whole kit, which will include the bulb, the ballast, and a reflector due to its ease of use and setup.
The best CMH light kits come with a ballast that operates using square-wave technology that will fix the electromagnetic interference issue that occurs with digital ballasts.
How to Hang and Position CMH Grow Lights?
For a 3 by 3 feet grow area, the CMH lights should be hung at a height of 2 feet above it to avoid burning due to hot spots, as well as spread the light evenly between plants.
A 4 by 4 feet area will be too big for the lights and the outer edges won’t be receiving the same amount of light.
They can also be placed vertically or horizontally to provide the best light arrangement for your grow area.
CMH vs. MH
As MH lights tend to be heavy on the blue part of the spectrum, the overall balanced spectrum of CMH lights is better especially with the added boost of red at 3100k and 4000k spectrums.
CMH lights emit less heat and they’re more PAR efficient when compared watt per watt. They also last longer than MH lights, as their lifespan is almost twice the amount of hours at 24,000 hours.
CMH vs. HPS
HPS is considered the king of flowering crops, as most of the PAR light it produces is a red light, which is perfect for plants in their flowering or fruiting phase. However, the amount of blue light it produces is not enough to cover their growth phase.
This results in weak and spindly plants.
Once again, the balanced CMH spectrum comes to the rescue, as it produces more PAR light per watt, which is best for every phase of the growth cycle. They’re also cooler than HPS.
A combination of both lights is the ideal arrangement for optimum plant growth.
HPS degrade a lot faster than CMH lights and will need to be replaced after the 9,000th hour.
CMH vs. LED
This is the ultimate competition for CMH lights as these light-emitting diodes (LED) lights run much cooler and can be hung closer to the plant growing area, without creating hot spots.
Because of their placement (6 inches above the canopy), however, LED lights can penetrate at a limited depth of 6 inches into the canopy, whereas CMH lights are hung 3 feet above and can penetrate at a range of 18 to 24 inches.
This means that LED lights are suitable for low ceilings and lighting underneath a canopy.
Although it may seem like a disadvantage that you have to replace the bulb with others that have a bit more red (3100k) or a bit more blue (4000k) for a specific growth stage, however, it’s more efficient than turning off the red or blue diodes in the LED lights.
This will limit the amount of light produced from the system significantly and reduce the overall efficiency of the lights, compared to that of CMH grow lights.
The upfront cost of LED lights is also noteworthy, as it costs around $900, which is almost twice or 4 times that of the CMH system. This makes CMH lights a more affordable option.
Some manufacturers of LED lights don’t provide factual information about their products, which can lead to under performing lights.
Our Thoughts
Growing plants indoors is an activity that should be enjoyable, however, it all depends on whether you’re using the right equipment or not.
The wrong equipment can make your yield smaller and your crops less healthy and dead-looking, which we don’t really want.
That’s why using any of our topics and understanding the way CMH grow lights operate and the differences among the types of lights will help you make a more informed decision.
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