How to choose a diffuser, and how to look after it
30 July 2026 · 2 min read · Monika Mazurek
Room size, the type of dispersal, and five minutes of cleaning a week — the three things that decide whether a diffuser lasts for years.
A diffuser is the commonest first purchase alongside the oils themselves — and the commonest source of disappointment, when it turns out to be too small for the living room or clogs up with residue after two months. Both problems can be foreseen at the point of choosing.
Match it to the floor area, not to the looks
Manufacturers give a range in square metres, and it is worth taking seriously. A model rated for 20 m² will barely register in the open space of a living room joined to a kitchen — the scent simply disperses.
- A bedroom or a study: a smaller model, quiet in use, with a night mode and dimmed light.
- A living room or an open space: a larger tank and stronger dispersal.
- Two smaller diffusers in different parts of a flat often work better than one large one.
Ultrasonic or nebulising
An ultrasonic diffuser breaks water with oil in it into a cool mist. It is quiet, cheaper, humidifies the air a little as well, and uses less oil — usually the right choice for a home.
A nebulising diffuser works without water, dispersing pure oil. It gives a distinctly more intense scent and fills a large space faster, but it is louder and uses oil considerably more quickly.
How many drops
Typically three to six drops per full tank. It is worth starting with fewer — a scent can always be strengthened, while an overdone one is hard to get rid of. An hour of running with breaks is usually more pleasant than running continuously all evening.
Five minutes of cleaning
This is the one thing that genuinely decides how long the device lasts. Citrus and resinous oils leave residue over time, and that residue blocks the transducer.
- After every use, pour out the remaining water — do not leave it overnight.
- Once a week, wipe the tank with a soft cloth and a little surgical spirit.
- Once a month, run water with a spoonful of vinegar for a few minutes, then rinse.
A diffuser cleaned this way runs for years and, more to the point, does not mix yesterday's scent with today's.
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