Hydroponics, by definition, is the process of growing plants in sand, gravel, or liquid, with added nutrients but without soil.
Hydroponics does not use soil, instead the root system is supported using an inert medium such as perlite, rockwool, clay pellets, peat moss, or vermiculite. The basic premise behind hydroponics is to allow the plants roots to come in direct contact with the nutrient solution, while also having access to oxygen, which is essential for proper growth.
Aeroponics is the process of growing plants in an air or mist environment without the use of soil or an aggregate medium.
Aeroponics is an optimized form of hydroponics where the roots are suspended in air, in a dark chamber. Plant roots are fed with a mist containing nutrients. The mist has droplet sizes ranging from 30 - 100 microns.
An electronic light source converts electrons into photons. Lights for human vision measure output with lumens (measured in lux or footcandles). Lights for photobiological reactions measure output with photosynthetic photon flux (PPF) or the rate at which the light source emits in the photosynthetic region.
Another way of stating it is: PPF tells us how much PAR a light source emits.
Where PPF measures total PAR output of a lighting system, Photosynthetic Photon Flux Density (PPFD) measures how much of that light is delivered to a given area.
For further information refer to our article and link to a video on PAR.
COB (Chip On Board), is a relatively newer LED technology.
COB LEDs are basically multiple LED chips (typically nine or more) bonded directly to a substrate by the manufacturer to form a single module. Since the individual LEDs used in a COB are chips and not traditionally packaged, the chips can be mounted such that they take up less space and the highest potential of the LED chips can be obtained. When the COB LED package is energized, it appears more like a lighting panel than multiple individual lights as would be the case when using several SMD LEDs mounted closely together.
Advantages of COB LED Technology
The light emitting area of a COB LED contains many times more light sources in the same area than standard LEDs could occupy resulting in significantly increased PPFD values.
COB LEDs use a single circuit with just two contacts to energize the multiple diode chips it houses. This results in fewer components required per LED chip for proper operation. Furthermore, the reduced components, along with the elimination of the traditional LED chip structure packaging, can reduce the heat generated from each LED chip.
The ceramic/aluminum substrate of COB LEDs also acts as a higher efficiency heat transfer medium when coupled to an external heatsink, further lowering the overall operating temperature of the assembly.
Another aspect of COB LEDs that reduces failure rates is the fact that spot soldering of the individual LED chips is not necessary as each chip is directly mounted onto the substrate. The smaller amount of welding points results in lowering the rate of failure.
With regards to grow lights COB LEDs are typically biased towards the blue and red wavelengths but typically offer a much more full spectrum than lighting panels with multiple individual lights. Figure 1, below, shows the "McCree curve". This data from a 1972 paper by Dr. McCree and Dr. Inada who performed several studies in the to determine the influence of light spectra on photosynthesis. Below in Figure 2 you will see the typical emission spectrum from the Sun, an HPS bulb, and the COB design that Indo Products uses. Figure 3 shows the emission from other LED panels, which are missing much of the PAR potential of a light. You will notice in Figure 3 that the emission is missing much of the light that is part of photosynthesis and therefore will likely not be as effective with plant growth if that is the only source of light a plant receives.
If your roots of the seedlings are protruding outside the growing medium (cube or puck) then they are ready to be be planted into pots or other growing medium.
Typically we would keep the light at a distance of 24” (60 cm) above the newly planted seedlings. Within a few days to a week you can start lowering the lights to a distance of 18” (45 cm). If the plants are growing and the leaves don't appear to be wilted (they are pointing up) they have adapted and will do best with a closer and stronger light.
If the seedlings appear a bit weak or you want to be on the cautious side you could start with only half of the lights on (with 800W and 1200W versions) at 24” height. However, after 1-2 days the seedlings should be well adapted to the stronger grow light and you can turn on all lights.
Keep zippers clean by brushing or wiping them regularly to remove dirt and grit that can become lodged in and around the teeth. If a tight zipper sticks, apply a thin coating of paraffin, talc or spray lubricant to the teeth.