3 Best CMH 315W Grow Light (Ceramic Metal Halide Reviews: Updated Aug 2021)
Ceramic metal halide lights are the ideal way to vegetate while using an HPS system, but finding a product that works well for you and your needs can be a bit confusing. Reviews across the web vary pretty greatly on individual products.
Power drain compared to the size of the grow and the room is the biggest concern when dealing with any kind of HPS system, so we need to factor this in when determining the best products for a grow. However, unlike a lot of HPS systems, a CMH doesn’t produce very much heat, so it does open up the option of spending more on lighting and less on ventilation.
Mostly, HPS systems are best for medium-sized grows where ventilation and other heating issues are accounted for within the setup. With this in mind let’s take a look at what we think are the best products on the market at the moment for CMH grow lights.
Advantages Of CMH Light
Spectrum
The CMH light spectrum combines the red-heavy HPS spectrum with the blue-heavy MH spectrum in one bulb, making it the perfect light for all stages of growth.
With a high CRI, it is extremely close to natural sunlight, which is great for your plants and for your eyes (plants look more natural, making it easier to spot any discolorations or other issues).
Efficiency
Ceramic metal halide gives you a much higher PAR (the amount of light that is usable by plants) per watt than any other type of lighting, apart from the most expensive LED fixtures.
UV Light
The CMH light spectrum also contains UV light of all types. Since UV-C light is harmful, the lamps use a glass filter to block that range.
This leaves only UV-A and UV-B light, which many feels is beneficial to yield quality. There is no need for supplemental UV lights when using CMH grow lights for indoor growing.
Lower Heat
CMH grow lights run much cooler than their MH and HPS counterparts. This reduces (or eliminates) the need for additional cooling equipment. They run hotter than light-emitting diode lights, though.
Long Lifespan
CMH bulbs last much longer than other HID or fluorescent lights. The standard rule of thumb for HPS or MH bulbs is to replace them after 10,000 hours of use. Good ceramic MH bulbs last over 20,000 hours.
Moreover, they still retain 80% or more of their initial light output after 20,000 hours. HPS and MH lamps deteriorate much more quickly.
ECO Farm CMH 315W Grow Light Fixture Reflector Enclosed Kit
Features:
The ECO Farm 315W CMH grow light kit is an efficient ballast grow light combo that is actually fairly low priced as well, it loses some points due to the light spread being a bit less stellar than advertised, but is a solid choice for those working within a budget. This is a decently designed ballast and reflector combo. The spectrum provided by the 315w ceramic discharge metal halide growth lamp kit is closer to natural sunlight than a typical high-intensity discharge (HID) system. The coverage area is 4 feet * 4 feet. Means greater harvest and lower cost. Finally, only a simple action can raise and lower the lamp. Locking mechanism 1/8" cord that can withstand up to 75 pounds of tension (150 pounds total)
DLI CRI Series 315w Grow Light
Features:
The DLI CRI-Series 315W DE fixture is made to grow plants. The output of the DLI CRI-Series 315W CMH fixture can not be adjusted. It can only be set to on/off and to the controller setting. By using the DLM-4 Zone Controller the fixture can be remotely switched and adjusted. The bulbs are super-efficient, with the red model producing 1.9 umol per watt and the blue producing 1.7 umol per watt — The highest efficiency SE lamp currently available. CMH lamps produce a spectrum that’s close to the sun’s spectrum at a high altitude. The extra UV produced by the lamp will add quality to your crop. As a standalone fixture, you should use red lamps throughout the flower over a footprint of 1m x 1m per fixture.
EYE Hortilux CMH 315W Grow Light System
Features:
The new EYE HORTILUX CMH 315 Grow Light System takes the next step for grow light systems. The short, compact reflector design maximizes light with 8% more light hitting the canopy and 30% more uniform light than the competition. The EYE HORTILUX CMH 315 Grow Light System includes a reflector that is easy to replace. After several grow cycles, system reflectors get dirty and sometimes scratched from cleaning. Having a reflector replacement schedule helps maintain consistent plant quality and high yields. Replacing a reflector in the CMH 315 does not require purchasing an entirely new system. This system will not accept Mogul Base lamps or CMH lamps that are not rated for open fixture use. Carefully install the lamp into the socket by inserting pins into matching-shaped holes in the socket and turning the lamp to right (clockwise). When the lamp is properly installed, the base will stop turning.
Buyer’s Guide
CMH lights are a great choice for those looking to advance past the heat of an old-school HPS system without giving up the brightness. However, there are quite a few things to consider before jumping into a major purchase like this.
Reflectors
A CMH bulb without a reflector will still produce the same amount of light, but it won’t spread to where you want it to well and mostly go to waste. Reflector designs vary when combatting this, but we look for the ones that have a limited amount of leakage.
We want a reflector that aims the light directly downwards, towards the plants. A good reflector will cover multiple plants, even up to 4–5 when made correctly. We look for systems that have a well-made reflector due to this, as a single CMH system should be able to handle a medium-sized grow easily with massive yields as a result.
Dimming
Different ballasts ask for more power versus lifespan out of a bulb. Depending on the size of your grow you should go for one that emphasizes brightness versus one that allows for adjustability in the wattage being produced by the bulb.
There’s a diminishing return with brightness where the size of the plant might not be worth the power drain. Generally, smaller grows of 3 plants don’t need the full brightness these lamps can produce.
In those cases, it’s good to look into a system that allows for dimming, as you’ll save money in the long run on purchasing a replacement. Furthermore, seedlings and smaller vegetating plants don’t need or even want the full power of these bulbs.
In these cases, the lamp has to either be dimmed or moved away. Dimming being preferable as the electrical cost and lifespan of the bulb can be spared.
Conclusion
With the above extensive review of CMH lights, we hope that you will know what to look out for when you are thinking of the kind of lighting system you want for your grow room. The lights are energy-efficient, they produce less heat per watt and their light spread is good. They are most suitable for the flowering and vegetative stages of crop growth and their lifespans depend on the models and wattage. Some of the lights come with great a UV light, which protects your crops from any harm.
