FAQ

Photo-synthetically Active Radiation (400-700 nanometers or energy units). PAR is a measurement of quantum units.  A nanometre (nm) is the measure of the wavelength, or frequency, of light.  A nanometre in billionths of a metre; the lower the number, the shorter the wavelength.

(Amount of light) When considered as a wave, light has a wavelength and a frequency. Light can also be thought of as a stream of particles, photons, or quanta. In this case, units can be expressed in moles per square meter per second (mol m–2 s–1), where “moles” refers to the number of photons (1 mol of light = 6.02 × 1023 photons, Avogadro’s number). This measure is called photon. It is used commonly to describe PAR in the range of 400-700 nm wavebands. Please see: Light Intensity and Duration and Daily Light Integral (DLI)

A photon at 400 nm, which is in the blue region of the spectrum, has twice the energy of a photon at 800 nm, from the red & infrared region of the spectrum. (400nm-800nm is used in reference to simplify the example of the mathematics).

A photon of 400 nm light contains 4.97 × 10–19 J. On the other hand, the 800 nm photon contains 2.48 × 10-19. The higher the wavelength of a photon, the lower its energy is.

Quantum meters use a photodiode to convert photon (light quantum) to measurable electrons. When using a quantum meter the figures that are measured are not of an exact science.

Why doesn’t a quantum metre report all photon wavelengths equally from 400nm-700nm (PAR)? Theoretically, a quantum meter should but a quantum meter may be more sensitive to red photons than blue ones, or may pick up green and yellow photons with much more accuracy than other wavelengths, so each model has error adjustments that need to be made after a reading is taken. This is only possible if you know the individual wavelengths that are emitted from a light source. The accuracy of quantum or PAR meters also are dependent on what type of light source you are measuring and LED’s typically have the most error (up to 15% or more).

To quantify a more precise and accurate reading we measured the available light with a piece of equipment called Spectro(radio)meter-spectrometer.  Spectrum (PAR) shows the strength of the light that is being emitted and also that it is in the proper wavelength proportion for what a plant can actually utilize.

These two measurement tools (PAR metre and spectrometre) produce a reading that shows not only what wavelength or color is being emitted, but also the absorption value of that particular wavelength.

We use average spectroradiometric data for each LED type to estimate lamp performance and perform these tests in a laboratory environment. In practice the majority of actual photo-metric results will vary, based on your growing environment.

A spectroradiometer operates in a much different fashion than quantum or PAR meters which is why they are more accurate, but also much more costly. Instead of using one or a few sensors to read all wavelengths like quantum meters do, a spectroradiometer handles the measurement of light much differently. Light enters through a series of optics in which can be changed depending on what type of light source is being measured. Once the light has exited the optics it enters an area called a monochromometer which uses different lenses and diffusion refractors to break the light into monochromatic light (one color) where each wavelength or color is guided through a tiny slit and read by a series of tubes and semiconductors which read each band of light separately. Please note that the tubes and semiconductors can be changed depending on what light source is being measured and this is why a spectroradiometer is the most accurate measurement device for determining what photons are being emitted out of a light source.

For example:A spectroradiometer can be used to take reflectance measurements in your greenhouse or fields to estimate defoliation. Chlorophyll gives plant leaves a reflectance spectrum characteristically different from that of soil. Reflectance measurements can be reported in μmol m^-2 s^-1, W m^-2, or as a relative value.

Yes, JUST LED US uses a radiospectrometer.  Please see the following readings for our varying chip sets as they can be used to contrast and comparison with other grow lights in the industry.

 

You can utilize the use of your COB Series lights horizontally, vertically, and diagonally as long as you leave space for you units to move air freely through the side vents.

Coming Soon! PAR measurements will be available to gear to specific plant group(s) in proper lighting category. These listings will be posted for various heights from the canopy and as well we will provide you with a detailed analysis of PAR/m2, µmol m^-2 s^-1

This will help you determine what light you may need when it comes to total canopy coverage and intensity from height positioning of the lamp itself.

Keeping the proper distance between your full spectrum LED grow light and your plants is important for photosynthesis and growth. Full Spectrum LED grow lights provide the wavelengths of light your plants need for germinating, growth/vegetation and flowering/fruiting.  The rule of thumb is to increase the distance between your light source and the top of your plants.

Depending on what model you choose there are varying distances suggested, please see our Chart regarding suggested distances for different models. The coverage area (m²）and PAR value will change according to the distance of which the light/lamp is placed above the canopy. This means that the High PAR COB Lens and Reflector Series grow lights have different power ratings and will perform best at different distances, with different plant families.

When your garden is in the vegetative stage maintain the above noted distances. To allow for plant stretching increase the distance from the plants to the light and for shorter, bushier plants decreases the distance. As you raise the light, the plants will reach for the source and grow taller, but it is important to note that raising the light source too high will cause excessive stretching. If you keep the light at an affixed height, the plants will reach a certain growth point, then grow wider and form more vegetation.

For flowering plants, the lights can be left at the affixed height and the daily light interval must change.

Full spectrum light is light that covers the electromagnetic spectrum from infrared to near-ultraviolet, or all wavelengths that are useful to plants.

 

The following pictures are examples of the spectrums used in our 25×3 watt and the 32×3 watt lights, the numbers are shown in nanometers.

3 Watt LEDs can reach the electric current limit as high as 700mA.  To sustain output and reach optimum luminous efficiency with respect to the expected lifetime of the unit we know from our laboratory testing that it is best for the LEDs electric current to operate in the range of 550 ～ 600mA.  When the electric current operates in the range of 550~600mA the life of your unit will be extended as the LEDs will not degrade as fast because the LED junction temperature and overall operating temperature will remain lower.  Some LED grow lights on the market are running at 90-100% and this usually results in degraded PAR value and shorter lifetime expectancy for their units, overall. Thus, 700mA wastes energy, costs more in electricity to power the unit and also the end user will find that they may have to repair their unit consuming valuable time and effort to change degrading parts over the lifetime of the unit.

Our 3 watt diodes run at 550 ～ 600mA driving current which drives the perfect blend of intensity, efficiency, durability, and low operating temperature, making them the superior choice. Many other LED brands are running with lower diode wattages and lesser driving currents, making them an inferior option when compared with the JUST LED US LED Grow Lights.

Some LED grow lights run well below their potential watts. If you have 100 X 3W LEDs the potential is 300 Watts but the actual draw will be lower, closer to 150 Watts. LEDs are usually driven at anything from between 50% to 75% of their potential.  If you run a watt for watt continuously you have a greater chance of color shift (Ex. 1 Watt at 1Watt continuously or a 3W at 3 watt continuously or 5 watt at 5 watt continuously) your PAR levels will change dramatically and the shift is irreversible.

Let’s get this straight; don’t be fooled into thinking that just because your LED grow light has 32 x 3watt LEDs it has an output of 96 watts. This is not a fact as mentioned above the bulb time will be severely limited and degrade if you power it at full capacity. Your LED grow light will have an output closer to 55% of its full capacity; this concept applies to all LED grow light diodes.

Yes, although our general line of lights are full spectrum we can customize your lamps to best fit your gardening needs. There are people who like to conduct research with supplementary lighting and we understand that it is important to have certain spectrum customizations. We realize that everyone will have different gardens and thus we further understand that specific needs are to be met for different plant families throughout their stages of life. For example, light is vital for photosynthesis, but is also necessary to direct plants growth and development. Light acts as a signal to initiate and regulate photoperiodism and photomorphogenesis. There are two light-sensing systems involved in these responses, the blue light sensitive system and the red light sensitive or phytochrome system.

Yes, plants take advantage of ‘full spectrum light’ when it is used throughout germination, vegetative and flowering cycles, and we must note that LEDs penetrate your plantation differently than older lighting technologies such as high pressure sodium and metal halide thus the usage of light differs as well.

You will have stronger plants and a consistent growth pattern when using full spectrum. You will further find that Internodal spacing is shorter while the stems stay stronger and are less prone to breaking as the plant expends less energy growing stems, and more energy producing flowers or fruits.

Yes! If you so choose to use supplemental LED lighting, slowly introduce it for short intervals as you will find that your plants may experience a shock when the additional light is present because of the introduction to a blast of additional spectrum and intensity, as they have to prepare themselves for the new amount of light they are receiving otherwise known as light saturation point.

Some people believe in older methodologies which pertain to the usage of light changes when (HPS & MH) are used so if you are adaptive to this system of analogy to maximize your yield we suggest chatting with us and you can order the chips to be customized according to what your needs are with 660 or 680nm (Red, Infra-red, and UV) if you so choose.

If you are a researcher, you may be interested in ordering specific spectrum or spectrum ratio  light to supplement your existing lighting system.

Most plant growth and morphology is commonly the same, plants grow up and outward. Plants will stretch upwards when the light source is at a constantly and kept at or above the suggested distance from the canopy and they will start to bush out and grow more dense if the light source is not changed. If your light is placed in a fixed position the plants will grow to a certain point and then they will grow in width.

 As mentioned above, generally there is a certain growth rate and common morphology to certain plant families, certain plants require different PAR ranges. This directly relates to what you want to grow and correlates to the intensity of light which is available accordingly to certain models as the growing area you have available is important in relation to this questions’ answer.

For instance, if you want to grow lettuce and it is going to be a small (vertical) garden we would suggest that you order a light without UV as a lettuce garden doesn’t really need UV as opposed to fruiting plants such as tomato or plants which you are going to make into essential oils.

However, there is evidence that has been shown by plant physiologists that when growing with UV though LED’s it makes lettuce darker and redder, therefore healthier because they are rich in antioxidants.

Another aspect to this answer lies with the experience & knowledge of the grower as UV-absorbing polyphenolic compounds form in its outer layer of cells. Some of these compounds are red and belong to the same family that gives color to berries and apple skin. They help block ultraviolet radiation, which can mutate plant DNA and damage the photosynthesis that allows a plant to make its food.

When it comes down to it, the units all cast a different PAR value and coverage Area（m²) based on their size. Smaller units will cover less area, where the larger units will cover more area and in some cases, depending on what you are growing you will have the ability to place the light source farther away from the canopy or growing surface – hence having a bigger garden.

 WARNING this device produces potentially harmful UV light.  Protect eyes and skin from exposure to UV light. Plants do have biological mechanisms for repairing damage to their DNA from UV. Humans also have these repair systems. UV can still be dangerous, so be sure to follow ALL the safety instructions for using your lamp

Wear UV-resistant safety glasses at all times around UV light sources! Always prioritize your safety and the safety of others.

Our patented optical reflector enhances the output and the PAR value of the LED which maximizes the yield of your produce and it is significantly important for a faster growth rate. They also optimize the investment of your return of commercial plant growing with superior quality. Depending on the model there are different angles which we use for reflectors, such as: