Complete Guide to Carbon Filters: How They Work and How to Choose the Right One for Your Growbox

When growing indoors, one of the main priorities is to eliminate the strong odors produced by the plants, which can often be very intense and persistent. The most effective solution is the use of activated carbon filters, essential tools for purifying the outgoing air and ensuring a discreet and safe cultivation environment.

This guide explains in detail how a carbon filter works, what technical parameters to consider, and how to choose the right filter for your growbox.

What is a carbon filter used for?

Activated carbon filters are primarily used to absorb and neutralize odors that escape from your growbox. The air extracted by the ventilation system passes through the filter, where odor particles are trapped thanks to the porous structure of the carbon.

In addition to exhaust systems, filters can also be used on air intake lines to clean incoming air from pollen, spores, mold, and other pollutants, creating a healthier environment for your plants.

How does a carbon filter work?

The core of the filter is made of granular activated carbon, a material with an extremely porous structure that can adsorb molecules present in the air. This means that odor molecules adhere to the surface of the carbon and remain trapped.

The CTC (Carbon Tetrachloride Activity) is a technical index used to measure the adsorption capacity of activated carbon. It is expressed as a percentage: the higher the value, the more compounds the carbon can hold.

• A carbon with a CTC70 value has excellent performance and is suitable for professional filtration.
• Values above CTC55 are still effective for growbox use and indoor cultivation.
• Avoid filters that do not specify the CTC value: you may end up with poor or ineffective filtration.

Max airflow and optimal airflow: what do they mean?

• Max Airflow: the maximum air volume (in m³/h) that the filter can handle without losing efficiency.
• Optimal Airflow: the recommended air volume for the best balance between filtration efficiency and filter lifespan.

How to calculate the right filter for your growbox?

1. Calculate the cubic meters: Width (m) × Depth (m) × Height (m) = Volume in m³
2. Multiply by 60: This gives you the ideal air exchange rate, based on 1 complete air change per minute.

Example:
Growbox 1.2 × 1.2 × 2 m = 2.88 m³
2.88 × 60 = 173 m³/h

You should therefore pair an extraction fan of at least 173 m³/h with a filter that has an optimal airflow equal to or higher.

Recommended Products on Idrogrow for an Ideal Setup

• Dobermann Tent 120x120x200 cm The ideal growbox for this type of setup.
• Vents TT125 Extractor Fan Airflow 220-280 m³/h, perfect for the calculated growbox.
• Airontek Odor Filter 125-250mm 300 m³/h The perfect filter for this setup.

Final tips

• The filter must always have a capacity compatible with the extractor fan.
• Replace the carbon filter every 12–18 months, depending on usage.
• Choose filters with a CTC value of at least 55% to ensure good performance.

FAQ – Frequently Asked Questions About Carbon Filters

Question	Answer
Why use a carbon filter in a growbox?	To eliminate strong odors produced by the plants and purify the outgoing air, keeping your grow discreet and hygienic.
Can I use a filter on the intake side?	Yes, it can also be used to clean incoming air from pollen, mold, and other harmful particles.
What is the CTC value?	It is an index that measures the efficiency of activated carbon in adsorbing molecules. A good carbon has a CTC of at least 55.
What does max airflow mean?	It is the maximum airflow the filter can handle without losing efficiency. Do not exceed this value to maintain performance.
What does optimal airflow mean?	It is the recommended airflow for optimal operation: it ensures the best performance and the filter's lifespan.
How do I choose the right filter?	Calculate the volume of the growbox in m³ and multiply by 60. Choose a filter with airflow compatible with the extractor fan.