How to Control Humidity in an Incubator
by Alexa Lehr | The Pioneer Chicks | April 18, 2023
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There are three essential conditions that chicken eggs need in order to hatch: heat, humidity, and turning. Humidity is necessary during incubation to control at what rate moisture evaporates from the developing eggs. Knowing how to control humidity in an incubator is essential for maintaining the correct humidity levels throughout incubation and at hatch time. If you are lucky enough to have an incubator that controls the humidity automatically, that makes your job that much easier! However, there are other ways that you can control the humidity levels in the incubator if your incubator is not fully automatic. Let’s take a look at 5 ways you can control humidity in the incubator!

Why is Controlling Humidity Important?

But first, why is controlling humidity important? In an early post I discussed how you can monitor humidity levels in the incubator. Digital hygrometers, wafer thermostats, egg air cell growth, and egg weight loss can all help you monitor humidity levels in the incubator. However, the whole reason you monitor humidity is to make sure the humidity levels are correct.

But how do you keep the humidity levels correct in the incubator? By controlling the humidity factors in the incubator. Humidity levels in the incubator are affected by how much moisture is in the air and where that moisture is coming from. You can control humidity levels in the incubator by controlling the sources of moisture within the incubator or by regulating air flow within the incubator.

It is important to operate your incubator at the ideal humidity level. This will ensure that the incubating eggs don’t dry out or contain too much moisture at hatch time. Here are the suggested humidity levels for incubating and hatching chicken eggs:

• Incubation (day 1-18): 45-55%
• Hatch (day 19-21): 65-70%

For more information on determing the correct humidity for incubating eggs on your homestead, make sure you head over to How to Monitor Humidity in an Incubator. If not controlled, humdity levels will naturally fluctuate within the incubator. Fluctuations will be affected by factors such as opening and closing the incubator, ambient humidity, air flow, and moisture sources within the incubator.

Controlling these factors is how you will maintain the proper humidity levels throughout incubation.

Note: Incubator Capacity & Humidity

If your incubator’s instruction manual has a recommended humidity level for using with the incubator, follow those guidelines. The egg capacity of an incubator will affect how much humidity is needed during incubation. Keep in mind that the suggested humidity level is based off of running the incubator at full capacity.

Eggs loose moisture throughout incubation and that moisture adds to the humidity in the incubator. The larger the incubator, the more eggs it can hold. The more eggs it can hold, the more moisture will naturally be added to the incubator air. That means you can often run a large incubator at a lower humidity level than a small incubator. That also means that if you don’t run your incubator at full capacity, you may need to make adjustments in the humidity level.

Once you have determined the correct humidity level that needs to be maintained in your incubator, you can go about deciding how you will control the humidity levels throughout incubation.

#1. Water Pans, Pots, Trays, & Grooves

The main way that you can control humidity levels in the incubator is by using the built-in humidity features of the incubator. Since incubator models vary by brand, the humidity features of different incubators may vary as well.

Most incubators have a water container of some sort. The container should hold water for adding moisture to the air within the incubator. The water container can be a pan, pots, divided pans or pots, grooves in the bottom of the incubator, or fillable trays that you can be add or remove. The water container will have to be filled with water at the start of incubation. You may also have to refill it several times throughout incubation depending on how fast the water evaporates. The only time you would not fill the water container is if you are doing a dry hatch and are relying on ambient humidity levels.

Some incubator models make it easy for you to fill the water container without opening the incubator. An external water container can be filled that will constantly make sure the water container within the incubator stays full. For other incubators, you may have to open the incubator to refill the water container.

In fully automatic incubators, you just need to program in the correct humidity level. Then make sure the water contain always contains water. An electronic pump attached to a digital hygrometer will then adjust the humidity within the incubator to ensure the humidity stays at the programmed level.

Controlling Humidity with Water Containers:

The way that water containers work in an incubator is by providing water surface area for moisture to evaporate from. Evaporation adds moisture (humidity) to the air. The amount of water surface area that is open to the air will dictate how much water evaporates at one time. Increasing or decreasing the water surface area is how you can control humidity levels.

Larger Water Surface Area = Higher Humidity

• larger water container/pan/pot
• fill more grooves
• add more water trays

Smaller Water Surface Area = Lower Humidity

• cover part of water container/pan/pot
• fill fewer grooves
• remove water trays

If the water source is open and accessible at hatch time, you will want to make sure the container is covered with a porous but protective cover. Most incubators should come with a water container cover. High humidity levels are needed at hatch but you don’t want newly hatched chicks to be able to access the water. The chicks could accidentally get wet and possibly even drown.

#2. Sponges & Wick Pads

Using sponges and wick pads is one way to increase humidity in the incubator. If you are monitoring humidity levels in the incubator and you realize that they are lower than what they should be, adding a moist sponge or wick pad can help increase the humidity.

Basically you are adding another source of moisture to the incubator. The added water source helps increase how much moisture evaporates into the air. Which then increases humidity levels in the incubator. This can be especially helpful at hatch time. During hatching, the humdity levels need to be kept high to prevent shell membranes from drying out as the chicks hatch. But also keep in mind that the moisture from hatched eggs will cause a spike in humidity each time a chick hatches.

One thing to remeber about sponges and wick pads is that they are not a constant supply of moisture. Once the sponge dries out, it is no longer useful for adding moisture to the air. Sponges and the like can help rapidly increase humidity levels after opening the incubator. They can be used as a short-term solution for low humidity in the incubator.

Here are some objects that can be moistened and used as a sponge or wick pad in the incubator:

• Hold Moisture Well: sponges & humidifier wick pads (cut to desired sizes)
• Dry Out Fast: cotton balls, folded paper towel, pieces of cotton cloth

Make sure you remove any objects that could be hazardous for young chicks at hatch time. You don’t want them eating pieces of cottonball or paper towel. Sponges and wick pads are often sturdier and won’t be as easy for curious chicks to accidentally consume.

#3. Ventilation

Regulating the ventilation on your incubator is another way to control humidity levels. Ventilation allows air exhange between the outside air and the air within the incubator. The warm, humid air will naturally escape from ventilation holes near the top of the incubator. Meanwhile, fresh air will be drawn in from ventilation holes near the bottom of the incubator.

This constant exhange and air flow is one reason why humidity levels would naturally fluctuate if not controlled throughout incubation. Some ventilation holes must always be left open throughout incubation. Developing embryos need oxygen and expel carbon dioxide. Having good ventilation ensures that old, stale air can be replaced with fresh, oxygen-laden air.

However, ventilation holes also allow humid air to escape the incubator and can pull in dry air. Ventilation and ambient humidity (discussed in a minute) go hand-in-hand.

To control humidity levels in the incubator by adjusting ventilation, your incubator has to have a way for you to open and close the ventilation holes. Some incubators come with plugs that you can insert into the holes or other incubators have covers over the ventilation holes that you can slide open and close.

• Opening Vents– allows humid air to escape and can help bring down humidity levels
• Closing Vents– traps humid air inside and can help increase humidity in the incubator

Remember, you always want to have some ventilation holes open no matter the humidity level.

#4. Ambient Humidity

Ambient humidity refers the humidity in the environment where the incubator is located. The humidity level in the incubating room will be a factor that affects how well the incubator can maintain constant humidity. High or low ambient humidity is based off of the ideal humidity you want in the incubator.

You can keep track of ambient humidity by placing a small digital hygrometer beside your incubator. The hygrometer will provide you with a digital reading of the humidity level in the incubating room. Ambient humidity will fluctuate with weather patterns, seasons, air conditioning, and air flow (ventilation) in the room.

If you want to maintain 50% humidity in the incubator, then an ambient humidity of 40% would be considered low. And likewise, an ambient humidity of 65% would be considered high. If the ambient humidity is lower than your target humidity, then you will need to use some of the humidity control methods we just covered for keeping the humidity level high in the incubator.

If the ambient humidity is 15% higher than your target humidity, then you will want to remove any extra water sources from the incubator and consider doing a dry hatch. A dry hatch relies on ambient humidity to keep humidity levels high enough in the incubator. However, if the ambient humidity lowers throughout incubation, you will want to place a water source back in the incubator to make sure the humidity levels don’t get too low.

#5. Water Temperature

The last way that you can control humidity in the incubator is by regulating the water temperature of the water that you use to fill water containers or dampen sponges and wicks with. In general, always use room temperature water when adding moisture to the incubator. Cool water would absorb heat from the air in the incubator and could cause temperature fluctuations.

Keep a bottle of distilled water near the incubator to use for refilling water containers or moistening sponges and wick pads. When refilling internal water containers, try to minimize how many times you open the incubator and how long the incubator is open. Opening and closing the incubator frequently will make keeping stable humidity and temperature levels more difficult. Plastic pipettes, containers with a pour spot, or funnels can all be helpful when refilling incubator water containers.

Aside from always using room temperature water, you can also use warm water to help increase humidity levels in the incubator. Warm water evaporates at a faster rate then cool water. Adding warm water to the water container in the incubator or moistening sponges with warm water can help quickly increase humidity levels. However, the warm water will not help keep humidity levels high over long periods of time.

You don’t want to use hot water in the incubator. Just like with cold water, hot water can make it hard for the incubator to maintain a stable temperature. The hot water can create steam which can cause the incubator to over heat and be hazardous for egg development. Incubated eggs can handle a small decrease in temperature better than an increase in temperature.

Balancing Humidity Control Methods

In incubators that don’t automatically control the humidity for you, keeping the correct humidity levels stable all throughout incubation can be challenging. First, always base your humidity control methods off of the incubator’s instruction manual for filling any water containers or grooves that are a part of the incubator design. Regulating how much water surface area is exposed within the incubator can be the most practical way for controlling humidity in your incubator. If the humidity level needs a little boost, try adding a warm, damp sponge or closing off some ventilation holes. If the humidity seems too high in the incubator, decrease some of the water surface area or remove the water source all together. Hopefully the five methods we covered for controlling humidity in the incubator will help you have a successful hatch on your homestead!

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