I’ve talked extensively about traditional HID and LED grow lights systems, but there’s a recent trend with a third new grow light system that you may not know about. Ceramic Metal Halides or CMH for short. I will be describing them here and also giving you my top picks for the best CMH Lights for 2020.
Are CMH Grow Lights Better than Other HID Grow Lights in 2020?
CMH lights were actually discovered in the 1980s but with recent discoveries and horticulture research, they’re beginning to catch more and more wind. So why are so many seasoned growers starting to ditch HPS to CMH grow lights? Right off the bat, once you turn on a CMH bulb, you’ll notice a much more natural-looking light spectrum, no strong orange or yellow hues like an HPS bulb or the bright white and subtle blues from metal halide. So why is it that Standard metal halide bulbs use a quartz arc tube. Whereas CMH use ceramics much like a high-pressure sodium lamp, and not only that, but there’s less degradation because of the stronger arc to material.
That’s why it operates at a much higher pressure than standard MH bulbs. The ceramic arc tube is necessary to slow down the caustic breakdown effect that the unique mixture of salts and halides use. It’s this mixture that creates the broad spectrum and then, in turn, gives growers the enhanced photosynthetic photon flux levels. Basically the claim is that your plants can enjoy and near full-spectrum white light, very similar to natural sunlight that lasts longer than your HIV counterparts.
How do CMH Light Color Compare to the “Best Light”
The color rendering index of the sun is 100. HPS lights are roughly 20 to 30 while metal halides are 60 to 65. CMH lights come in at 90 to 92 making them only about eight points off from our most natural sunlight. An added bonus aside from the quality of the spectrum is a lower heat output and power consumption with lower Watts. That means you’re going to have less heat in your tent and less of a toll on your electricity bill.
How do CMH Lights Compare in Heat?
So to break it down, one watt from a grow light creates about four BTUs of heat that needs to be cooled. In comparison, one 600 watt HPS light puts off about 2,400 BTUs and one 315 watt CMH light puts off only 1,260 BTUs, which is almost less than half the HPS light. With all that being said, with CMH lights in your tent, you’ll be running a much cooler tent and having to run your AC a lot less, keeping your electricity bill down. So with only 315 Watts, the CMH bulb is stated to produce far more PAR in a grow area than a 600-watt HPS bulb. But with all of these claims, there’s one question. How much better?
In order to prove or disprove this, tests inside a four by four grow tent were done. Several different grow lights were hung at the top and the thermometer was placed right in the middle of the tent. Each light was run for 30 minutes, then the temperatures were checked. First was a CMH light. The starting temperature was 74 degrees Fahrenheit. The CMH grow light raised the temperature to 86 degrees. So in total, the CMH raised the temp of the tent by nine degrees in 30 minutes. Next, the 600-watt HPS grow light was tested. The starting temperature was 80 degrees. After running for 30 minutes, the temperature rose to 96 degrees. The increase on the HPS was a total of 16 degrees. A duel 315 Watts, CMH light and a new 450-watt prototype led grow light were also tested.
The starting temperature on the dual CMH was 76 degrees and after 30 minutes it had increased to 100 degrees. So in total, the dual CMH raised the temperature by 20 degrees. Lastly, was run the 450 watt led prototype. The starting temperature was 72 degrees and after 30 minutes it had raised to 82 degrees. That’s a 10-degree increase. When comparing the heat test results, the CMH ran the lowest increase of nine degrees. This was followed up by the led prototype with a 10-degree increase. The HPS had a 16-degree increase while the dual CMH closely followed with a 20-degree increase.
What are the PAR Differences in HID Lights?
Now that we can clearly see the differences and key output by these lights, we can then run PAR tests to measure the light intensity between the CMH, the HPS, the LED, and the dual CMH. These are the results.
This is a snapshot of the PAR charts. All lights were hung 36 inches or three feet above the ground. The 630 watt dual CMH grew light emits the most intensity out of the four charts, a strong 900 to 700 par rating in the middle and an average of 500 par in the outer area. If you were growing four plants in a four by four area, each plant will receive a near consistent light coverage throughout its growth cycle.
Under the dual CMH, there is a significant difference in PAR rating between the duals 630 Watts CMH and the single 315 Watts CMH. Coverage is still consistent overall, but a single bulb impacts intensity in certain applications. I recommend using the 315 watt for smaller grow tents or only utilize it for the vegetative cycle. The traditional HPS 600 watt bulb shows the second most intense light with the test showing 600 to 700 PAR ratings in the middle of the canopy and tapering off to 500 to 300 and the outer area.
When looking at these numbers, in conclusion, I would rank the dual CMH as the most intense light in these tests. Couple that intensity with the quality of spectrum, you can’t go wrong with this type of setup, using a grow tent in any home grow.
How are they for Spectrum?
Looking at these graphs, you’ll notice a few impressive features that the CMH bulbs have versus the HPS grow bulbs. One major difference is how complete the CMH spectrum is, and not only that but the addition of stronger UV production. The HPS grow bulbs are very focused on the near red spectrums, which is great if you’re utilizing the HPS bulb as your one-trick pony for flowering.
The CMH 3000 came with its wide array of available spectrums that makes it a full cycle bulb. We recommend the three K bulb from clones to flowering, and the four K is a broader spectrum bulb that leans towards the more vegetative focused plants. It can be used to supplement for flowering, but the three K is more than adequate.
The 315 watt CMH bulb is equivalent to a 600 watt standard HIV grow life when it comes to spread. However, the light is more intense, provides a higher quality spectrum and has half the cost and half of the heat. CMH bulbs will cost you more out of pocket, but in the long run they’ll save you much more money. It’s the best possible lighting for in-home growing. It’s cheap to set up efficient, runs cooler than an HPS or double-ended bulb, and with the standard of over 1.3 grams per watt for hemp growers, new growers can’t go wrong.
The Best CMH Grow Lights for 2020
There is a lot of selection in CMH lights but all of the reviewers (and myself) agree on these top five for the best CMH grow lights for 2020.
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1. VIVOSUN 98% ULTRAHIGH REFLECTIVITY 315W CMH GROW LIGHT
HIGHEST REFLECTION/BEST ECONOMY
- PROFESSIONAL RESULTS MADE EASY: This CMH fixture run significantly cooler compared to conventional lighting setups and do not need to be cooled with ducting and fan, they can simply be air-cooled and are really energy efficient
- HIGH-TECH BALLAST: Cutting-edge adjustable ballast features advanced low-frequency Square-Wave technology for high efficiency, reliability, and no electromagnetic interference. 8′ power cord with 3-pronged plug, compatible with Standard North American outlets (with 120V to 240V adapter included)
- ULTRA-HIGH REFLECTIVITY RATING: Sturdy reflective hood is made of Italian VEGA aluminum rated at 98% reflectivity; the contour design and texturing eliminates hot spots and dead zones
- GROW LIGHT COVERAGE: VIVOSUN recommends use of this unit to cover an area of approximately 9 square feet during vegetative growth and approx. 6 square feet during the bloom phase
- EFFICIENT, FULL-SPECTRUM LIGHT: This fixture delivers a more efficient spectrum for growing than HPS systems. PGZ18 lamp socket. 3-year warranty
VIVOSUN 98% ULTRAHIGH REFLECTIVITY 315W CMH GROW LIGHT: THE VERDICT
This 315 W fixture does a decent job. It is highly energy-efficient, plus you do not need any sort of cooling fans, as it can be air-cooled. However, if your plants are placed in an enclosed space, then you will surely need to vent. I definitely recommend the VIVOSUN 98% Ultrahigh Reflectivity 315W CMH Grow Light. Click HERE to learn more!
2. Sun System LEC 315
The Sun System Light Emitting Ceramic Metal Halide light is by far the best option on the market in 2019. Nothing else really comes close in terms of quality. Naturally, that means it’s a bit more expensive than most competing brands, but if you can afford it, it’s worth the extra cost.
It includes everything you need to light your plants, so you can just plug it in and start growing. You get an all-in-one hood reflector, which means it contains the ballast needed to power the lamp. The bulb socket is at the top of the hood, so the bulb hangs vertically. This makes for a more even light spread than a horizontal bulb.
The inside of the hood is 98% reflective German aluminum with 95% reflective textured corners. This ensures optimal output and uniformity, meaning you are losing as little light as possible from the reflection and there are no hot spots that can burn your plants. It gives you a coverage area of 4 by 4 feet.
Along with the quality hood, the kit also includes a Philips Master 315W CMH bulb. The kit linked to here includes the 3100K bulb, but there is also a kit available with the 4200K bulb instead. The 4200K bulb is better for vegging, so some growers use it if they are getting a light for the whole grow cycle.
Personally, I think the 3100K does fine with vegging and it’s so much better at flowering, that I would just go with that one for everything unless I was going to use the light for vegging only. Basically, the increase in vegging efficiency of the 4200K spectrum is more than offset by the increase in yield of the warmer 3100K spectrum.
The Philips bulbs have an initial lumen output of 33,000 and a very high 1.95 PPF (photosynthetic photon flux) per second. In short, they give you a huge output considering they only consume 315 watts. Their open rated construction reduces radiant heat from the arc tube. As a result, this kit runs much cooler than a comparable HPS or MH light.
Furthermore, these lamps last a long time, with an expected lifespan of 20,000 hours. More importantly, they retain 90% of their lumen output after 8000 hours of use and still retain 85% of their PPF output after 20,000 hours. It should come as no surprise that this quality bulb is also our recommendation for the best CMH bulb (see below).
The ballast included in the reflector is a 50/60 Hz low frequency, square wave, electronic ballast, with a rated lifespan of 50,000 hours. Square wave is a newer technology that provides a more constant maximum voltage to the lamp, resulting in a more steady light. Also, their lower frequency means no issues with RF interference.
The whole Sun System CMH kit is covered by a 1-year warranty and there is also a 240 V version available. It gets a Grow Light Info rating of 4.8 out of 5.
- All-in-one construction — ballast is built into the hood, making this kit much more compact than others
- Bulb hangs vertically — more even light spread than a horizontal bulb
- Huge amount of light — given the 315w consumption, the bulb gives you a huge 33,000-lumen intensity
- Long lifespan — the high-quality bulb is rated for 20,000 hours and retains 85% of its PPF output in that time
- Square wave ballast — no issues with RF interference and a much more steady stream of light
- Low heat — this light does not need to be ventilated
- Free ratchet hangers — a free set of ratchet hangers is included
- High price — higher price than competing lights, but, as usual, you do get what you pay for
Check it out on Amazon HERE!
3. SunStream 630W Double Bulb CMH Grow Light System Include Bulb
Of course, because this is a double bulb system, it is much more expensive than the single bulb units. Of course, the coverage area and light intensity is that much more as well. The three-year warranty shows that this company stands behind its fixture. It features:
- PROFESSIONAL RESULTS MADE EASY: This CMH fixture runs significantly cooler compared to conventional lighting setups and does not need to be cooled with ducting and fan, they can simply be air-cooled and are really energy efficient
- HIGH-TECH BALLAST: Cutting-edge adjustable ballast features advanced low-frequency Square-Wave technology for high efficiency, reliability, and no electromagnetic interference. 8′ power cord with 3-pronged plug, compatible with Standard North American outlets
- ULTRA-HIGH REFLECTIVITY RATING: Sturdy reflective hood is made of German aluminum rated at 98% reflectivity; the contour design and texturing eliminates hot spots and dead zones
- GROW LIGHT COVERAGE: SunStream recommends the use of this unit to cover an area of approximately 9 square feet during vegetative growth and approx. 6 square feet during the bloom phase
- EFFICIENT, FULL-SPECTRUM LIGHT: This fixture delivers a more efficient spectrum for growing than HPS systems. PGZ18 lamp socket. 3-year warranty of ballast and 1-year warranty of lamp
4. Best CMH Grow Bulb: Philips Master 3100K GreenPower Elite Agro 315 Watt CMH Lamp
The Philips Master 3100K GreenPower Elite Agro 315 Watt CMH Lamp is as good as it gets.
It gives you 33,000 lumen of intensity, which is incredible for a bulb that only uses 315 watts. Moreover, it retains 90% of that after 8000 hours of use.
The rated lifespan of this CMH lamp is 20,000 hours and even at that point, it still retains 85% of its initial PPF, which is an unbelievably high 1.95 PPF (photosynthetic photon flux) per watt per second.
Philips uses a unique open rated grow lamp construction that reduces radiant heat from the arc tube and makes their bulbs perfect for open fixtures. Simply put, they emit far less heat than comparable HPS and MH grow lamps, greatly reducing the need to cool your grow space.
The grow bulb we’ve linked to in this review has a 3100K color spectrum, which is our preferred bulb to use for all stages of growth. It is a flowering monster and does well in vegging too.
There is a 4200K version available as well, the Elite MW 4200K Master Color CDM Lamp, for indoor growers who plan on only using it for vegging or for those who prefer a full-cycle bulb with more blue spectrum light (to me, flowering performance is the most important).
- Huge output — given the 315w consumption, this bulb gives you a huge 33,000 lumens
- Long lifespan — the bulb is rated for 20,000 hours and retains 85% of its PPF output in that time
- 1.95 PPF/w/s — incredible efficiency, with very high lumens per watt consumed
- Low heat — this light does not need to be ventilated
- High price — higher price than competing brands, but as usual, you do get what you pay for
Click HERE to find out more on Amazon
5. Best Budget CMH Bulb: Protopia CMH 315 Watt 3100K
If you’re looking to save some money on grow bulbs, there are a lot of options available, considering that the Philips grow lamps are among the most expensive. Unfortunately, many of the cheaper models simply are not very good. An exception is the Protopia 315 watt 31ooK CMH bulb.
In terms of intensity, this grow bulb is actually more powerful than the Philips initially, with an output of 37,000 lumens. The problem is that this deteriorates much more rapidly than it does with the Philips. In fact, the rated lifespan of this bulb is only 15,000, a full 5000 hours less.
The PPF per watt per second is also lower, at 1.81. This means the bulb is not as efficient as the Philips bulb at turning the power you feed it into usable light. All that said, given how much less the Protopia grow light bulb costs than the Philips bulb, it is definitely worth considering. It easily outperforms other similarly priced ones.
The version we linked to has a 3100K color temperature, but there is also a 4200K version available. You’ll find it on the same page as the 3100K CMH bulb—simply select the 4K color option to check that one out.
- Low price — costs considerably less than the brand above
- Huge initial output — the Protopia beats even the famous brand above with 37,000 lumen
- 1.81 PPF/w/s — great efficiency, with very high PPF per watt consumed (but not as high as the Philips)
- Faster deterioration — the grow bulb becomes less bright much more quickly than the previous grow bulb above (but similar to most others)
- Shorter lifespan — the Protopia does not last as long as our top choice for indoor growers
Conclusion: Best CMH Grow Lights for 2020
I hope that this blog was informative as to what CMH lights are and which ones you might like. There are great selections for the inexpensive to the more expensive – depending on your needs. For myself, I feel that the Vivosun is the best CMH Grow Light for 2020 and has been in subsequent years. It is not overpriced and really delivers. Anybody who is into grow lights has to have heard of Vivosun! The other options are excellent as well and I hope this has made things a bit “brighter” for you! Please feel free to follow and share and please make sure you give your comments below, especially if you have your own favorite!