CMH (Ceramic Metal Halogen) 

CMH (Ceramic Metal Halogen)
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Ceramic metal halide (CMH) lamps offer several advantages over sodium vapor lamps (NDL) and conventional metal halide (MH) lamps

Firstly, they can withstand significantly more heat due to the ceramic elements used, which has a particular effect on the light emitted by the lamps. With the exception of the so-called green gap at a wavelength of approx. 510 nm, plants primarily require light in the spectrum from 420 to 680 nm for photosynthesis. In contrast to ND lamps, which can usually serve exactly one wavelength, and MH lamps, whose light spectrum is characterized by individual peaks at different wavelengths, a CMH lamp emits a very natural light that is very similar to that of the sun and is more or less constantly strong across all wavelengths. This can be illustrated in concrete figures by the so-called color rendering index (CRI); this value describes the quality of artificial light compared to natural light emitted by the sun. This is why the sun has the maximum possible CRI of 100, while sodium vapor lamps achieve values between 60 and 90. CMH lamps have a value above 90, which guarantees a high quality light that almost completely covers the light spectrum

Your plants are therefore enormously supported in their photosynthesis, which in turn has an effect on growth and ultimately on the yield. Compared to MH or ND lamps, you will achieve a noticeably higher yieldwith ceramic metal halide lamps.

At the same time, CMH lamps are excellently insulated, which means that they emit less heat and the risk of burning the plant (as can occur with sodium vapor lamps, for example) is significantly reduced.

The comparison with LEDs at this point is mainly in terms of price, since these could theoretically be individually adapted to the particular case of need. In any case, it is certain that most CMH lamps, just like their NDL and MH relatives, are usually much less expensive than LEDs of the same wattage class

However, there are also some things to consider with CMH bulbs. Due to their ability to reproduce an extremely natural and therefore full spectrum of light, UV radiation emitted from the lamp can be a factor in some circumstances. While this is filtered by the tube itself and usually has no effect on your plants or on you - if the tube is damaged, however, there may be a risk of burns or eye damage if you work under the lamp for several minutes. Therefore, if your CMH lamp has external damage, it is advisable to only work on your plants during dark periods until the bulb has been replaced.

Furthermore, CMH lamps work with a low operating frequency. This means that high-frequency ballasts are incompatible with the lamps and you have to use ballasts specially developed for CMHs (e.g. the Prima Klima Lucilu ballast).

Nevertheless, ceramic metal halide lamps have many extremely beneficial properties that are sure to benefit the growth, yield and health of your plants. Even if their popularity is not yet equal to that of NDLs or LEDs, they have long ceased to be an insider tip and are a real alternative on the market.