When growing indoors it’s usually necessary to use at least some artificial hydroponic lighting, and with the technology today there are a wide variety of lighting options (bulbs, fixtures and systems, etc.) available. Most widely used are High Intensity Discharge (HID) lights, also known as Metal Halide (MH), and High Pressure Sodium (HPS).
The larger wattage the bulb the more light, and generally speaking, the better plant growth will be. However these lights (as well as all the components of the lighting system) create heat.
MH and HPS lighting systems produce a lots of heat, this heat needs to be properly managed in a way to continuously maintain the optimal temperatures for your plants. Environments that are to hot and/or dry will stress the plants, and stressed plants just won’t produce well.
For most indoor growing situations the plants will produce better, and have better quality when the temperatures don’t reach above 85°F at the tops of the plant (nearest to the light, and heat source). Some of this heat can be vented from the lights using ducting with inline hydroponic exhaust fans, and/or using fans directly on the plants, or even by adjusting the height of the lights.
Listed below are some exhaust fans to get you started, also read through our article on Getting Bigger Yields from your Hydroponics Plants with goes over how to use the exhaust fans.