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High Intensity Discharge lamps are a high output light source. The light is created by sending an electrical discharge between two electrodes and through ionized gas. The HID lamps require ballast in order to generate the initial surge of electricity needed to start and to regulate the lamps power during normal operation. Indoor Sun HID lamps are specially made for greenhouse and horticultural applications. 


In the vegetative stage; plants mainly require blue spectrum, otherwise known as cool colour. These wavelengths encourage and trigger a greater vegetative response and healthier root zone. This is the foundation for a healthier and heavier flowering plant.


MH lamps (Metal Halide) are the best lamp option for the plants in the vegetative stage. These lamps can supply a colour temperature of 4000K - 6000K. 

Colour Temperature is a numerical value to the colour emitted by a light source, measured in degrees of Kelvin(˚K). The Kelvin Colour Temperature scale imagines a black body object (such as a lamp filament) being heated. At some point the object will get hot enough to begin to glow. As it gets hotter its glowing colour will shift, moving from deep reds, such as a slow burning fire would give, to oranges & yellows, all the way up to white hot. Colour temperatures over 5000K are called cool colours (bluish white), while lower colour temperatures (2700 ~ 3000 K) are called warm colours (yellowish white through red).




Plant growth (photosynthesis) is not determined by units of measurement generally used for the human eye such as Lumens or lux. Instead, determined by the photons from the blue to red spectrum   (400 - 700 nm). Within this range, plants receive optimal level of growth and flowering. The rate of photosynthesis is determined by the amount of photons between 400 - 700 nm. This growth light is called Photosynthetic Photon Flux (PPF) and is the only reliable light measurement term used to validate if a light source is suitable for plants. 

The higher the PPF value per watt, the more efficient the light source for plant growth and maximum yield.


HPS lamps (High Pressure Sodium) are the leading artificial source to produce PPF for the plants. HPS lamps have a mostly yellow and red, warm colour light. The red light causes plants to develop heavier flower and fruit, and recommended for flowering stage. Indoor Sun HPS lamps are engineered to produce the maximum PPF and highest PPF/W for the horticultural industry. 


Based on the maximum PPF and efficacy the Indoor Sun HPS series is classified as follows:

HPS PRO              



HV SERIES are lamps which have a voltage as high as 265V, however are known and marketed as 400V. All the Double Ended lamps are HIGH VOLTAGE. They work with lower current (amps) which causes less power loss and lower temperature, resulting in a higher lifespan of the ballast. They provide higher values of PPF & PPF/W than low voltage standard lamps.


  • A plant needs the specific light parameters for growing and producing flowers. 

  • Important parameters for the Vegetative stage are Colour Temperature (CT) and Blue spectrum

  • Important parameters for the flowering stage is PPF


Ceramic Metal Halide Lamps (CMH) are the best artificial source to meet all the required light parameters for the full cycle plant life. They also have the best Colour Rendering Index (CRI) within the HID lamp family. 

Indoor Sun CMH lamps are designed to provide the optimum CT, PPF and CRI for the plant.



CRI (Colour Rendering Index) is measured on a scale from 0 to 100. Sunlight has a CRI value of almost 100%.The higher the CRI, the more the colour of light being emitted resembles sunlight.


Generally, the UV spectrum is not suitable for plant growth, flowering or fruiting. When higher trichrome production is required UV lamps can be used for the finishing stage only (final two weeks maximum). Once the flower is formed and maturing, the UV spectrum can be used to activate the defence mechanism making the plant produce greater levels of trichrome. 

Indoor Sun UV lamp provide smooth UV spectrum to fulfil the requirements for the finishing stage.
* Warning: always use glass and cover skin while using UV lamps.


Ultraviolet (UV) is an electromagnetic radiation from the light source with a wavelength from 10 nm to 400 nm. Based on the wavelength of the spectrum, there are different kind of UV such as UV-A , UV-B, UV-C, etc. 

  • UV-A or black light, cannot be absorbed by the ozone layer

  • UV-B is mostly absorbed by the ozone layer

  • UV-C is completely absorbed by the ozone layer and atmosphere 

Indoor Sun PRO UV 315W 10000K lamp is UV-A


Why are there different wattages for the same application?

Indoor Sun lamps supply different lamp wattage to suit different growth stages and environments. Different lamp wattages have different light intensities and coverage areas. The hanging distance from the lamp to the top of the plant canopy is the major factor for choosing the lamp wattage size. 


Example 1:
If the lamp distance is too far from the plant canopy, the light will not be as effective. In this case, a lamp of greater wattage should be used or the hanging distance of the light should be reduced. 


Example 2:
If the hanging distance is too close to the plant canopy, the plant will receive excessive light (light saturation) resulting in burning and stress to the plant. In this case, reduce the lamp wattage or increase the hanging distance.


The recommended minimum hanging distance between the lamp and plant canopy for different lamp wattage is provided in the table below by Indoor Sun products. 


From the recommended minimum hanging distance, the light coverage area is an important factor. Lucius Ballast are recommended because the ballast boost option will increase light output by 10 to 15%. The light coverage area also depends on the type of reflector, which directs the light to where it is needed most. 

Therefore, a suitable light coverage area for different wattage range of the lamp is provided in the table below by Indoor Sun lamps.


For more information about lamp selection, go to

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