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About LEDs

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Do LED grow lights put off heat?

Yes, every light produces heat.  It does not matter if the light comes from a bulb, diode, or a star like our sun; they all produce heat.  LEDs provide a more efficient means for converting energy to light than other methods and therefore produce less heat, but they can not break the laws of physics. Physics dictates that anything that consumes electrical power will emit heat; claims that LED lights don't produce heat are entirely false-- just ask any physics teacher.

While LED lights still generate heat, there are important differences between traditional lighting technology and LEDs:

  • HID lights (metal halide, high pressure sodium and ceramic metal halide) require heat to produce light by arcing electricity through selected gasses, making them extremely hot, to the point the gasses glow.  This means HID bulbs themselves are extremely hot-- hot enough to start a fire, and many gardens have gone up in flames because of this danger.  LEDs’ electroluminescence technology is entirely different and does not require heat to produce light; LEDs themselves will not get hot enough to start a fire.
  • Much of the energy used by HID lights is emitted as infrared light (above 800 nanometers). This “light” is not usable by plants and only works as a “heater”, warming up the plants -- and everything else under the light.  This is why HID light feels warm on your skin, while LED light does not.  Our LED grow lights don't waste energy creating unusable and detrimental infrared light; all the energy goes toward growing your plants.
  • Because LEDs aren’t wasting energy producing light plants can’t use, we can use less energy overall to get the same (or better!) growth from plants.  Less energy consumed means less heat; for a given growing area, LED lights will put off less heat than any equivalent artificial light.

What is the difference between "LED Watts" and "True Watts"?

LED diodes are rated based on the amount of power (wattage) they can theoretically handle, if they are perfectly cooled. Excessive heat causes LEDs to degrade ("burn out") and makes them shift the color of light they are giving off, so in the real world LEDs are never run at their full rated wattage. This means that "LED Watts" is a completely useless number for comparing the light output from two different lights-- for example, you can have two "500 LED Watt" lights, with one running 100 watts of actual power through the LEDs, and the other running 300 watts of actual power.

Many companies selling LED grow lights only use the LED watts to advertise their lights, as the number is always larger and more impressive than the actual power draw, but it really tells you nothing about how much wattage is actually being used to produce light. The only reason we include LED watts on our website is because so many people request it as a means of comparison (for which it is completely useless-- actual wattage is the most accurate means of comparing relative power of any plant grow light).

Are white LEDs efficient for growing plants? What about these 10-watt white LEDs?

First, it is important to know what "white" light really is. White is not a spectral color, but rather a combination of different light colors. Human eyes only have 3 kinds of color-sensitive cells called cones-- red, green and blue-- and any light which stimulates all three of these at similar levels will appear white. There are many different ways that humans perceive white light from the combination of different component colors. Equal amounts of red, green and blue light, even without any other colors, will appear white to the human eye. Yellow light stimulates both the red and green cones, so blue and yellow light combined will also appear white. This is just one example; there are many, many other combinations which appear white to the human eye, even though the light is not a complete spectrum.

LEDs' electroluminescence technology (how LEDs make light) is not capable of producing white light directly from the diodes; individual LEDs can only produce one color of light. The first "white" LEDs were actually red, green and blue (RGB) LEDs combined, and indeed the light appears white to the human eye. However, if you view something that only reflects orange light under the RGB light, it will appear black, as there is no true orange from the light source that the object can reflect back. This means that RGB LEDs have a poor Color Rendition Index (CRI).

Almost all "white" LEDs on the market today are actually just a blue LED with a phosphor coating which converts much of the blue light into different colors. The most commonly available "white" LEDs use a phosphor called Yttrium Aluminium Garnet (YAG) which predominantly creates yellow light; the combination looks white to the human eye and has a much better Color Rendition Index (CRI) than RGB LEDs due to the wider spectrum created by the phosphor. However, 20%-40% of the light produced by the blue LED is lost in this process, so these "white" LEDs cannot be as efficient at creating light as a pure-color LED (and LED's cannot be made to produce a "pure-color" white). White LEDs are good if you're looking to illuminate your home or office as this efficiency loss is easily justified by being able to see comfortably, but for growing plants they are wasteful.

Plants preferentially absorb red and blue light. Much of the light produced by "white" LEDs are in spectra (colors) that plants do not use. This unused light is just converted to heat within the leaves, requiring lower environmental temperatures to maintain optimal leaf surface temperatures. When combined with the 20%-40% efficiency loss, white LEDs are less than half as efficient for growing plants than the correct mix of pure-color LEDs-- white LED grow lights force you to cool your growing environment more, just like HPS and MH, losing a lot of the other advantages LEDs offer.

We've investigated the newly-available 10-watt "white" LEDs for growing plants, but our 5-watt pure-color LEDs produce more usable light, require less cooling, and use half the electricity.

What is beam angle and why is it important?

It's easy to be confused by the idea of beam angle and how it can affect plant growth. Each individual diode (LED stands for Light-Emitting Diode) has a cone-shaped lens that can be designed to focus the light coming from the emitter anywhere from 30° to 180°. In LEDs, beam angle refers to this angle of the light cone the primary lens creates. It is important because it determines the intensity of light reaching the plant as well as the total effective footprint of the light.

HID (MH / HPS) bulbs have a 360° beam angle- half the light produced is aimed up and away from your plants, which is why a reflector is needed to try and reflect as much of this light as possible back down to your garden. LEDs in general are more efficient at growing plants than HIDs because LEDs only produce light aiming toward your plants. Properly-designed LED lights that use an optimal beam angle in the primary lens have no need for a reflector.

Each diode in every Black Dog LED grow light uses a 120° lens, which is the best angle to achieve a large footprint with intense light covering all of the growing area. Many other companies sacrifice the footprint in order to achieve better canopy penetration by using a 60° or 90° lens, or even use secondary lenses to further focus the light into a narrow cone; this is often the only option with weaker LEDs. Black Dog LED's PhytoMAX and Universal Series lights use only the most powerful 5-watt chips, so we can use a more oblique angle to create a generous, evenly-covered footprint while still maintaining superior canopy penetration.

Watt-for-watt, our lights have the largest, brightest, most evenly-covered footprint of any LED grow light on the market so you can grow healthier, high-quality plants everywhere in the footprint. We maximize your yield rather than just the reading from your PAR meter directly under the light!

What is the difference between 1, 3, 5 and 10 watt diodes? What are COB LEDs?

When looking at LED grow lights there are many specifications thrown around about different types of LEDs. For the uninitiated this can be very confusing. If you want to learn what these different terms mean, check out our blog post that explains what these are and how they affect your indoor gardening.

Do LED lights require a ballast like HID lighting?

No, LEDs don't require a ballast. HID lights require a ballast in order to generate the extremely high voltage required to initiate the electric arc inside an HID bulb. LED lights operate in a completely different way and don't need a ballast; they do require direct current (DC) but this power converter is built in to our LED fixtures.

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