You have many options when providing light to your hydroponic system. Natural lighting is by far the least expensive option; since, after all, the sun is free! But many people at one time or another will grow under artificial lights to save the plants from a sweltering summer or frigid winter or to experiment with different colored lights to encourage particular growth stages.
But you can also choose between growing with high-pressure sodium lights and LED lights:
The main difference between growing with LED lights and high-pressure sodium lights is the amount of heat produced. High-pressure sodium lights run hot. In a growing room using high-pressure sodium lights, the ambient room temperature will be ten degrees less than the temperature under the lights. With LED lights, the room temperature and temperature under the lights are the same.
Temperature plays an important role when selecting which lights you will use. Most plant canopies do best under a temperature of 85 degrees Fahrenheit because the plant leaves are releasing moisture as they absorb more water and nutrients through their roots. High-pressure sodium lights, if placed near the canopy, increase the temperature interacting with the plants. When growing under LED lights, you will not have to calculate the temperature produced by the lights, but you might need to adjust the room temperature of where you are growing.
You should also pay attention to the humidity levels that your plants are exposed to. Again, humidity plays a role in how the plants can evaporate water. Many plants prefer a humidity level of forty percent when growing under LED lights.
Spacing and hanging your LED lights will also be different than working with sodium lights. LED lights are available in different light wattage amounts, which will have different core and total footprints. This means the entire area that the LED light will cover with light when hung. Pay attention to the core and total footprints when hanging your LED lights so that all plants are exposed, and the intensity under the light and the intensity between the lights are the same.
For instance, the 180 watts LED grow light from ProSource Worldwide features a two-foot core footprint and a three-foot total footprint. These lights should be hung so that the center of each light is two feet away from each other. That way, the plants beneath the light receive direct light from the LED, and the plants growing under the spaces between the lamps receive indirect light from the multiple lamps around them.
The height at which you hang the LED lights above the plant canopy is also related to the strength of the lamps. For a 180 watt LD light, twelve to fourteen inches from the bottom of the lamp to the top of the canopy is an excellent distance to promote growth. LED lights with lower wattage should be hung closer to the canopy, and LED lights with more substantial wattage should be suspended further from the canopy.
Plants can grow spectacularly under LED lights but pay attention to the differences between these and traditional light bulbs.