Air Exchange

Air exchange and circulation is an essential part of any indoor plant growing setup.  Adequate ventilation in the grow room is vital for a number of reasons including temperature, humidity, disease control, odour control, and fresh/stale air exchange. How to correctly design a ventilation system for your grow room  involves a number of calculations, that, when done right, will help your plants thrive in a well ventilated environment.

Here are some basics on the main factors to consider – 

Air Circulation and CO2

Plants need CO2 for photosynthesis. In badly vented rooms, the plants consume the CO2 available in just a short time. If this is not replenished, photosynthesis will come to a virtual standstill and your plants will stop growing.  

Simple gas physics – ‘warm air rises, cold air falls’, so good air circulation is essential for a balanced air mixture and proper circulation ensures a better CO2 absorption by the plants. Stationary air around the leaves rapidly looses its CO2 content to the plants and replenishing the air helps maintain good CO2 availibilty. 

The average concentration of CO2 in air is 300-500 ppm(parts per million), but by increasing the CO2 levels of your growing environment to between 1,200 and 1,500 ppm, plant growth can increase by as much as 30%.  However, in order for the plant to maximise the higher CO2 availability other factors must be at their optimum, namely water availability, temperature and light hitting the leaves.  
 An obvious point to make is that when the lights are out, there’s no photosynthesis, so don’t waste you CO2.  If you regulate your CO2 supply make sure it’s on a timer to synchronise with the light hours your plants receive.

Inadequate ventilation slows down the growing process. In addition, proper ventilation, together with regulated humidity levels, prevent fungal growth and the movement of the plants ensures stronger stems. .  Here are three links to the key sections giving a range of top quality products and brands –

Fan-Filters Section 

COSection for CO2 generation products.

Air Circulators section 

Air Humidity

Each day growers take litres of water into the growing area. If there is not enough ventilation, the air humidity will rapidly become more than 80%. This aids fungal growth, which can cause serious problems at the flowering stage. Therefore, you should keep air humidity at between 40% and 60%.

We have an extensive range of Fans and Humidity Control products to help prevent and solve humidity problems.


The presence of HID (High Intensity Discharge) lamps in the growing area can cause the temperatures to rise to over 87°F(30°C). Such temperatures are harmful to your plants as they have a severe impact on the essential plant processes needed for strong, healthy growth. Proper ventilation ensures that the day time(lights-on) temperatures will be about 79°F(26°C) and night time(lights-off) temperatures are generally within a 10-17°F(4-10°C) lower temperature range.  Consider using room heaters to ensure the right temperature range is maintained during colder months, so your plants don’t suffer the stress conditions that inhibit your plants’ development. Inadequate temperature control as well as circulation(see below) can lead to a whole range of pest and fungal issues that can cripple a plant’s health and growth…so beware!

We have a range of heaters in stock.