How do I size a dehumidifier for a grow room?


Plants transpire about 97% of the water they receive, so the amount of water your plants consume is approximately the amount that needs to be removed each day.
For example, 30 plants each receiving ½ gallon per day is an average of 15 gallons water per day. Every gallon of water is 8 pints. This example works out to 120 pints per day. Check out our Savings Calculator to find the best humidifier for your needs to improve your growing condition.

Isn’t my air conditioner a dehumidifier?


Yes, but there are issues with this solution.

  1. Air conditioners remove water only when they are running. In most cases when the grow lights are off, the air conditioner is off as well. Lights-off time is when humidity is most problematic.
  2. Using an air conditioner to dry a room will overcool the room, potentially causing plant stress. This will also use a significantly greater amount of energy than a Quest commercial dehumidifier.
  3. The more energy efficient the air conditioner, the less moisture it actually removes. An efficient air conditioner is a terrible dehumidifier.
  4. The re-heat method. Some air conditioners offer an optional heating coil as a dehumidification option. Essentially, by adding artificial heat to the room, the air conditioner is forced to operate when the lights are off and thus the air conditioner removes water. While this method works, and can be used in a pinch, it’s a poor long term solution and will use 4-8x the energy as a Quest dehumidifier. 4-8x the energy use is roughly equal to $5,000-$25,000 per year in unnecessary energy consumption.

What if I live in Arizona or New Mexico, do I need a dehumidifier?


While it may be dry outdoors, growing in a sealed environment changes things a good bit. Growers using sealed rooms, even in the driest of outdoor climates, almost always require dehumidifiers. The higher quality of the grow room design and construction, the more critical a dehumidifier will be.

What is the ideal humidity?


Because every plant is different, it is hard to pick just one number. However, most research indicates that 45-55% RH is the safe zone where plants are healthy, spore germination is unlikely, and pests find the environment unappealing.

How much money does a Quest dehumidifier save me in electricity?


Quest is the leader in energy efficiency and one of our models is the most energy efficient dehumidifier ever built. Depending on the model, Quest dehumidifiers can save commercial growers $100-$200 a month in electricity per unit. That’s $1,200-$2,500 per dehumidifier per year.
Check out what you could save.

Can the water be reused?


Yes, Quest dehumidifiers produce neutral pH, very low TDS water. This water is safe for all plants, even consumable ones.
Check out the laboratory test results.

How do I install a Quest dehumidifier?


Installing a Quest dehumidifier is simple, just plug it in and turn it on. We recommend hanging the unit above the lights in a room. There are many products available to help with this at any well-stocked hardware store. The two simplest methods involve threaded rod and metal rails or heavy duty chain.
Here is a quick video showing how we hung one:

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