May Scoop Light Science CMH Lamps – The Science Behind the Hype

Light Science May 2018

CMH Lamps – The Science Behind the Hype

CMH Lamps – The Science Behind the Hype

First distributed into commercial applications in the mid-90s, ceramic metal halide (CMH) lamps have advanced significantly over the past twenty years. As the technology has improved and awareness increased over the past several years, CMH lamps have become a product of choice for plant growth lighting in many regions of the US and, more recently, Canada.

CMH lamps differ from traditional quartz metal halide in that they contain an arc tube made of a ceramic composite. This small ceramic capsule can operate at a higher temperature and allows for more ideal mixtures of gases and chemicals.


Ceramic metal halide is typically 10%-25% more efficient than quartz metal halide. Therefore, lighting systems utilizing CMH lamps can either be more efficient (less watts, same output) or produce more light (same watts, more µmol). As an example, certain growers claim that two 315W systems (approximately 670 watts input to the ballast) have higher yield when compared to one 1000-watt system having 1,080 input watts.

CMH lamps have superior color rendition with a spectrum close to that of the sun. CMH lamps tout a spectrum that is up to 95% that of sunlight (fully rendered blues, reds, etc.). In comparison, the output of most HPS lamps is typically around 25% to 30%.

Low-watt CMH lamps operate on square-wave ballasts which provide a more constant maximum voltage to the lamp for a longer period of time. In effect, this produces more photons of light energy over the same period of time.


Currently most CMH systems are 315-watt or derivatives thereof, having two or three 315 watt capsules (i.e. 315-watt, 630-watt (2 capsules), 945-watt (3 capsules)). Sunmaster is currently working on several dedicated high-watt CMH designs including single-capsule 600-watt and 860-watt products. Let us know what CMH products you or your customers may be interested through www.sunmastergrowlamps.com/contact

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