Saturday, May 1, 2010

The Importance of Ventilation in Hydroponics

Fresh air is at the centre of successful indoor gardening. Outside, air is abundant and almost always fresh. C02 levels in the air over a field of rapidly growing vegetation will vary on how still the air is. Being outdoors, and subject to the warming and cooling of the day, the wind blows in fresh air. Rain will cleanse the air of dust and pollutants.

The outdoor environment is always moving. Plants grown indoors do not have the natural balance that is present out of doors and must be achieved indoors by way of fresh air ventilation or CO2 enrichment.

So you have decided to add CO2 to your hydroponic systems. Great! Welcome to the wonderful world of bigger yields. Now having said that, there is a caveat – like all good things – there can be some events to watch out for. For our purposes we will be dealing with the increases of humidity in a CO2 enriched environment.

Now what is humidity? Simply put – humidity is the water vapor present in the air.

There are various devices used to measure and regulate humidity called psychrometers or hygrometers. You can regulate the humidity of a room with humidistat a variety of tools in your growing arsenal. These are comparable a thermometer and thermostat for temperature control. You can find from most retail outlets combination hygrometer/thermometer unit – we recommend looking for a quality wireless unit for ease of placement.

The humidity level should be in the range of 40-75% when your lights are on which can be measured with a hygrometer. Now the warmer the air, the more retained water- this means humidity levels can easily go beyond the recommended 40-75%. High humidity like this coupled with lower nighttime temperatures (a requirement to get plants like orchids to bloom) can cause condensation to form on leaves. Which means your hydroponic system would be a prime candidate for all sorts of fungus issues, like powdery mildew. Inadequate ventilation is the primary cause of most fungal diseases.

How do you prevent this?

Ventilation fans – both intake and outtake- help regulate temperature, CO2 levels and relative humidity. During the winter months, you're more likely to need a ventilation fan for dehumidification rather than reducing temperature. Air is not exchanged as frequently in winter, so plants naturally raise humidity without air being exhausted. Fans at too high a setting combined with high heat can lead to lower humidity levels as well – find the balance for your hydroponic system and it will take care of itself.


These remove heat, which accumulates rapidly in indoor growing situations. Excess heat can result in excess humidity as the air retains for water. By pulling air in the side of the blower and pumping it out the front. For mounting on a wall or inside a grow box units have a flange on the front. Some feature a round inlet flange for connecting ducting so you can pull air from another room.

Keep fresh air flowing, and watch your indoor garden grow!


  1. What a nice comment i like it so much, Guys what a blog putting by u i really like it thanks for this type of blogs.
    Good atmosphere makes good results. Air circulation plays an important role in keeping the atmosphere clean and safe. Air which comes through the openings of the buildings gets heated and circulates in the atmosphere with dusts and gaseous particles. It never gets out of the workplace. You have to do something to push it outside.
    Thanks again.


  2. Fresh air is the heart of all successful indoor garden. In Outdoors, the air is very rich, almost always fresh. In indoor the level of oxygen and co2 should be well maintained. I like this information about ventilation very nice!!

    Healthy Hydroponics

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