Definition - What does Dehumidifier mean?
A dehumidifier is a device that removes moisture (humidity) from the air. They are often required in an indoor garden or growroom. Removing moisture from the air is vital for preventing many moisture-related diseases and conditions, ranging from mold and mildew to root rot and more. Without the proper humidity levels, plants cannot thrive and grow.
A dehumidifier is the opposite of a humidifier, which adds water back to the room.
MaximumYield explains Dehumidifier
Indoor gardening is an ideal solution for many people who lack the ability to grow outdoors. This may be because they lack outdoor space for a garden, or because the plants they’re growing are simply poorly suited to the environment. However, indoor gardening, whether using containers or a hydroponic system, comes with several challenges. One of those is keeping humidity levels within the healthy range. A dehumidifier removes excess moisture (humidity) from the growing area.
Excess moisture in the air builds up quickly within an indoor environment. When outdoors, wind and sunlight, as well as variable humidity levels, help to keep plants healthy and wick away excess moisture. This does not occur in an indoor garden, so growers need to take steps to prevent the humidity from rising too much. Too much moisture in the air can cause rot, mildew, mold, and other various plant diseases.
A dehumidifier will pull excess moisture from the air, and either collect it in a removable pan for disposal/dumping, or allow it to drain through a tube that can be routed outside, or into a collection vessel. Note that the water removed from the air can usually be reused in your indoor gardening application somehow.
All forms of indoor gardening will benefit from using a dehumidifier to control the level of moisture in the air, but hydroponic systems will absolutely require one. Choose a dehumidifier that is rated for the amount of moisture you have in your indoor air (calculated by the number of gallons used per day, multiplied by eight).