ONA Block


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ONA Block



The ONA Air Freshener Blocks are a combination of 32 different essential oils set in a wax-like block. Simply place the container where you are having problems with bad grow room odours, open the lid and the block begins to do its job! Any odours in the vicinity are completely eradicated, leaving you with a fresh smelling house. As the blocks evaporate they will shrivel up and lose their effectiveness, so make sure you replace each ONA Block air freshener as and when needed.

ONA Blocks are available in two scents; Fresh Linen and Pro. Fresh Linen’ masks and eliminates grow room smells and leaves in place the sweet scent of freshly washed clothes. The Pro version is the most effective at removing and replacing bad or unwanted plant smells, but the smell is slightly more ‘industrial’ than the Fresh Linen version.

The ONA Blocks are ideal for combating bad odours in a smaller environment (like a single bedroom). For larger areas, you may need to make use of the ONA Gel. The blocks are best placed in the area you are concerned you will get unwanted odours and not in the actual grow room itself. They can also be positioned in the ducting throughout your extraction system as a fail-safe to your carbon filter. All the extracted air is forced over the block as an extra means of odour masking.


ONA Block Air Fresheners works via the secret blend of 32 essential oils. This broad spectrum of oils works in a variety of ways on unwanted odours, not just masking any prevailing odour, but also neutralising them too. As ONA Blocks use only natural, food grade ingredients they are 100% non toxic, so health and safety to people is of minimal concern.

The essential oils work by three distinct different modes of action. This ensures that unwanted plant smells are both masked and, to a degree, removed. The three modes of action are as follows:

Absorption – The smells (or volatile organic compound’s (VOC’s)) are completely retained within the compounds released by ONA Blocks.

Adsorption – Similarly to how activated carbon works in filter’s the unwanted VOC’s are essentially stuck onto the surface of the compounds released from ONA Blocks

Chemical Reaction – Permanent bondage of the odour molecule and the active ONA Block ingredients. Particularly through the ‘Zwaardermaker Pairs Theory’, where two or more VOC’s can form a natural bond/attraction and cancel each other out.

A typical hydroponic grow room will contain plants that are creating and releasing all sorts of VOC’s, a class of which being terpenes. Terpenes and other VOC’s evaporate faster at higher temperatures, so you are likely to notice hot days being more problematic than cool ones. Terpenes and other VOC’s have a wide range of physical characteristics, so the 32 oils having these three modes of action to remove smells gives you peace of mind for a great price.


You can increase the length of time they last for by piercing holes in the lid rather than opening up the entire thing. The reduced air flow over the waxy block will slow down the rate at which it expires.

On the flipside, if you have an excessively smelly room that needs some intense treatment, you can take the waxy block out of the container altogether. This exposes its entire surface to the air, meaning you get the maximum air freshening effect possible, although this does significantly reduce its longevity.

Keep a few spare ONA blocks handy, when they do run out, it’s always best to be able to replace them straight away rather than risk smells making their way out.


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