A CMH lamp has a different emitter than a normal metal halide lamp, which is built of Quartz. Inside a CMH there is a ceramic component. So the difference is this A ceramic tube is able to withstand much higher temperatures. Many manufacturers are saying the higher arc tube temperatures happening inside the lamp allow for more color stability, better lumen per watt ratios and effectively an all around better bulb in comparison to the HPS metal halide. Were talking about how many photons of light youre getting to your plant in the usable spectrum per watt of input, which is really the way you want to measure efficiency for your lamps.
CMH lamps burn just like a normal Metal Halide Lamp. There are salts inside of the arc tube that heat up to a high temperature and that give off a certain spectrum. But, since the salts inside a CMH are able to heat up to much a high temperature theyre actually turned into what resembles plasma. Plasma burning at this higher temperature has the effect of providing a spectrum that is much wider and better than traditional HPS or metal halide lamps.
Without question, the quality of yield is increased when a plant is grown under a CDM grow light as opposed to HPS grow light due to a broader and more natural (closer to sunlight) spectrum of light emitted. The enhanced spectrum of light emitted from a CDM grow light will increase complex sugar production and essential oils within a plant in comparison to a standard HPS grow light, and in doing so will enhance the flavor of produce and increase the overall quality of yield. This enhanced spectrum of light will also produce stronger plants that are more resistant to pests and diseases and will also reduce plant stretching. So thats why these ceramic metal halide lamps are so popular these days because people are looking for the little edge in getting every efficiency of their garden possible.
Warning: When CDM HID (High Intensity Discharge) lamps are switched on they run extremely hot. As with all HID lamps it is necessary to avoid touching the lamp with anything such as fingers or plants as this may cause severe burns or fires. In particular, avoid sprays or liquids coming into contact with the lamp as this may cause premature failure or even an explosion.
We recommend to never handle the glass of your bulb always use a soft cloth.