Do You Need a Dehumidifier in Your Fish Room?

4 min read

Although aquariums give an aesthetic touch to your home, they come with a humidity problem. Water evaporates from the aquarium, making the air in the fish room saturated with moisture above the recommended level of 30 – 50%. Do you need a dehumidifier to resolve this problem?

You need a dehumidifier in your fish room to dry the air and maintain the relative humidity at or below 50%. Dry air prevents damp conditions, which supports the growth of molds, mildew, and fungi. This protects your fabrics and keeps you from respiratory diseases.

This article details why a dehumidifier is necessary for your fish room, how it works, and the size you need. Plus other ways to supplement your dehumidifier’s efforts.

Why You Need a Dehumidifier in Your Fish Room


Most tropical fish survive in a temperature range of 75-800°F(24-270°C), which is higher than the average home temperature of 68-720°F (22-240°C). This temperature difference can cause up to 1 gallon (3.78 liters) of evaporation daily.

The high evaporation rate increases the relative humidity, which refers to the amount of water the air can hold when saturated. Chances are, your house’s relative humidity will soar above 50%, which is a danger to your property and health. You’ll start to notice:

  • Musty odor
  • Condensed moisture on items such as windows
  • Growth of mold and mildew on fabric, wood, and carpet

Effects of High Relative Humidity

Humidity has some negative effects that one needs to look out for. These include:

  • Damaged household items: Moisture forms wall pockets, destroying drywall, wallpaper, and paint. It also supports the growth of mildew and molds on things such as wood, resulting in soft rots which require professional attention.
  • Respiratory diseases and allergies: Fungi, molds, and dust mites survive in humidity of above 55%. Inhaling the spores leads to a runny nose, sneezing, and skin rashes.
  • High energy consumption: Humid air is always warm. So, you’ll need to use an air conditioner to cool the temperature. Thus, spend more on energy.
  • Increased maintenance costs: When mold grows on items such as wood and HVAC, you’ll need to incur professional fees for repairs and maintenance.

How a Dehumidifier Helps

Muggy conditions can tempt you to quit rearing your fish. However, you can maintain a moisture-free environment with a dehumidifier. Here are the ways it helps:

  • Drying air: The dehumidifier absorbs the water saturated in the room, leaving the air at or below 50% relative humidity. No mold, fungi, or mildew can survive low moisture, which helps preserve your property and health.
  • It removes musty smells: A dehumidifier leaves the air fresh by removing a damp odor that makes the room stuffy and uncomfortable.
  • Reduces energy consumption: Air with less moisture is cool, so you won’t have to use the air conditioner as much.
  • Preserves water: You can use the condensate you collect in the dehumidifier to water plants instead of discarding it.

How a Dehumidifier Works

All dehumidifiers work on a similar principle of removing moisture from the air through condensation. The temperature in the dehumidifier remains cooler, pulling water from warm air in the room and cooling it into a condensate. Here is how it works:

  • The dehumidifier’s fan rotates to draw warm, humid air inside.
  • Cold temperatures inside convert the moisture in the air into liquid via condensation.
  • The dehumidifier reheats the air and releases it back into the atmosphere.

Here’s a YouTube video explaining how a dehumidifier works:

There are two types of dehumidifiers that determine how you collect the condensate.

  • Desiccant dehumidifiers: They have wheels coated with a desiccant or moisture-absorbing material such as silica gel. You remove water from the desiccant by passing steam or hot air.
  • Refrigeration dehumidifiers: Moisture collects on coils and drips into a collection bucket through pipes.

What Size of a Dehumidifier Should You Use?

Dehumidifiers vary in size depending on how much moisture in pints per day or PPD they can remove. The sizes range from 10 to 100 pints (4.73 to 47.31 l).

Below is a table to help you determine the size of a dehumidifier you should use.

ConditionCharacteristicHouse Size in Sq.Ft. and Dehumidifier Capacity in Pints
200 – 500 sq ft (18.6 – 46.45 sq m)600 – 1000 sq ft (55.74 – 92.9 sq m)1100 – 2500 sq ft (102.19 – 232.26 sq m)
DampClammy atmosphere10 pints (4.74 l)20 – 40 pints (9.46 – 18.92 l)Musty odor and damp spots on house items such as carpets and walls
Very dampMusty odor and damp spots on house items such carpets and walls20 – 30 pints (9.46 – 14.2 l)30 – 50 pints (14.2 l – 23.66 l)50 – 60 pints (23.66 l – 28.39 l)
WetDamp smell and sweat on items40 – 50 pints (18.92 – 23.66 l)50 – 60 pints (23.66 – 28.39 l)70 pints (33.12 l)
Very wetDamp odor and stagnant water on the floor50 pint (23.66 l)60 pint (28.39 l)70 – 100 pint (33.12 – 47.32 l)

Other Ways of Reducing Humidity in Your Fish Room

Apart from using a dehumidifier, there are other preventive measures to reduce humidity in a fish room.

  • Cover your fish tank with a 6 – 8 mm (.24 – .32 in) double wall of polycarbonate sheet to reduce evaporation.
  • Ensure proper ventilation in the fish room by installing a humidity control fan.

Final Thoughts

While having an aquarium is a great hobby, you must prepare to deal with excess humidity in the fish room. Moist air can cause damage to your property and allow allergens such as fungi and molds to grow. But, with a dehumidifier, you can always afford to keep the air dry.


Written by:

Pet Aquariums

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