When you are growing in a hydroponics environment, it is important to have light and lots of it. In hydroponics the more light you have, the better your plants will grow. However there is a trade-off. More powerful HID lights will use more electricity and also give off more heat. So there is always a compromise between high-powered lights and dealing with the heat. The idea is you want to use the most powerful light you can, but not raise the temperature in the environment of your hydroponic system higher than what the plants are comfortable with. Plants are usually comfortable in the same temperature range as humans. For this reason you need to have clever ways of dissipating the heat away from your garden.
This article will deal with the most efficient ways of keeping your high-intensity lights cool, so that your plants can maintain a healthy rate of growth.
Probably the most common and easiest way to keep your lights cool is to use an air cooled light reflector. These types of air cooled reflectors house the bulb inside of a reflective housing, and also has a piece of glass on the bottom separating the bulb from the plants. Essentially the glass on the bottom of the reflector holds all the heat from the bulb and keeps it from reaching the plants. So any heat that is generated by the bulb will stay within the reflector, and not be allowed to interact with your plants.
Often with this type of air cooled reflector set up, you will have a fan blowing cool air over the bulb, as well as another fan that will often pull hot air out of the environment and move it somewhere else. Generally you want to get that heat as far away from your plants as possible, preferably into another room. That way only a cool air from the room is being passed over your bulb. By trapping hot air inside the reflector you can keep the light closer to your plants, and therefore maximize the light without burning your plants. Essentially the closer the light is too your plants the more efficient that light will be. By using an air cooled reflector you can easily achieve this and gain maximum yields.
Lately a new invention has come into the market place that will surround water around your lamp. Essentially your light bulb is enclosed within two glass tubes. Coldwater from a chiller is then passed over your bulb keeping it cool and dissipating the heat. This will allow you to keep your light extremely close to your plants with no temperature issues whatsoever. However it is really dangerous putting this much water and weight on top of your garden. Hot lights and cold water and electricity do not mix, so this I technique for dissipating heat is not recommended. However if you want to take the risk be prepared to have to suspend a lot of weight of the water. And also operate a large quarter horse power water chiller to keep plenty of cool water surrounding your lamp.
Instead of using HID lights you can also opt to go with either LED or fluorescent lights. However neither type of light will produce as many lumens as a high pressure sodium or metal halide lamp. Even though these lights will run a lot cooler and generate less heat they will not give you as big of a yield. You are much better off using HID lights with an air cooled reflector to achieve maximum yields. Do not believe the hype of the LED and fluorescent light manufacturers. The pros do not outweigh the cons of a smaller yield.
You will get your best yields by using an air cooled HID reflector.