What is CleanLight's UV technology?
The short version: UV-C light destroys the DNA of powdery mildew, botrytis and other pathogens on contact, in seconds, with no chemicals and no residue.
What is UV-C?
UV-C is ultraviolet light at 254 nanometers, the germicidal wavelength. It has been used for decades to disinfect hospitals, drinking water and food production lines. When UV-C hits a fungal spore, bacterium or virus, it disrupts the organism's DNA so it can no longer reproduce. The infection cycle stops.
Why 254 nm?
Ultraviolet light covers a band from about 100 to 400 nanometers. UV-A and UV-B, the part that reaches the earth's surface and the part some grow lights add, do not disinfect at the doses used on plants. UV-C sits below 280 nm, and the low-pressure lamp in every CleanLight unit emits almost all of its energy at one line: 254 nm. That line sits close to the peak at which DNA absorbs ultraviolet light, which is why it has been the standard for water and air disinfection for more than fifty years. A spore that absorbs enough 254 nm light cannot copy its DNA, so it cannot germinate or spread. Not every 254 nm lamp is suitable for crop protection: the dose has to be high enough to reach a spore on a leaf in a few seconds and low enough not to damage the plant. That balance, lamp output plus reflector plus working distance, is what CleanLight has calibrated since 2006.
How CleanLight applies it to crops
Raw UV-C would damage plants at high doses. CleanLight's innovation, developed in the Netherlands since 2006, is a calibrated dose delivered through a parabolic reflector: strong enough to destroy pathogens on the plant surface, gentle enough to leave the plant unharmed. A daily sweep of a few seconds per plant is all it takes.
The reflector does two things. It shapes the light downward and into the foliage, so the dose reaches leaves, stems and bud sites rather than scattering into the room, and it shields the person holding the unit from direct exposure. The lamp needs about one minute to warm up to full germicidal output; after that it delivers the same dose on the first plant and the hundredth.
How long does a treatment take?
With the CleanLight Pro (36 W) we advise 5 to 10 seconds per plant, sweeping slowly across the canopy from the distance given in the manual. A tent with ten plants is a two to three minute routine including warm-up; a dedicated room of thirty plants takes about five minutes. The CleanLight Hobby (11 W) delivers roughly a third of the output, so each area needs around three times as long, which is why we recommend the Hobby only for a single small tent. During an active outbreak, treat twice a day until the symptoms subside, then return to the daily pass. Our article on how many plants a handheld unit can treat per day has the full table.
The CleanLight Air works differently: it is wall-mounted, runs continuously, and pulls room air through a filter and past an enclosed 60 W UV-C lamp. There is no treatment time to plan. You switch it on and leave it running, and it lowers the number of live spores in the air of a room up to 100 m³ (3,500 cu ft) around the clock.
Why growers choose light over chemicals
- Zero residue. Nothing is sprayed, so nothing shows up in lab tests. Usable through flower and even post-harvest.
- No resistance. Fungi adapt to chemical fungicides over time. They cannot adapt to having their DNA destroyed.
- No re-entry intervals. Treat and keep working. No protective-equipment downtime, no waiting periods.
- No license required. UV-C treatment is allowed on all types of cultivation.
What the research says
Independent trials at Simon Fraser University tested a CleanLight Pro on cannabis plants under constant powdery mildew pressure. The peer-reviewed study (Scott and Punja, 2021, Canadian Journal of Plant Pathology) reports 45% less powdery mildew with a daily UV-C pass of a few seconds per plant, even though treatment only started after infection had set in. The independent SFU trials that preceded it found up to 86% less powdery mildew with a daily UV-C routine; used preventively, from the first day of flower, results sit at the top of that range. The method is the same one every grower uses at home: warm up, sweep, repeat daily.
What it controls
CleanLight is effective against pathogens that live on the plant surface: powdery mildew (preventative and curative), botrytis / bud rot (preventative and surface-curative), fusarium spores, and bacteria and viruses on plants, surfaces, water and air. Botrytis that has already grown into plant tissue cannot be cured, which is why daily prevention is the winning strategy.
What it does not do
UV-C is a surface tool. The light only reaches what it shines on, so spores hidden deep inside a dense cola, or rot that has grown into the tissue, are out of reach. It does not repair leaves that are already damaged, and it does not replace humidity control and airflow. Used daily alongside a dry canopy and moving air, it closes the gap those two leave open: the spores that land on the plant between one day and the next.
The routine
- Let the unit warm up for about one minute.
- Sweep the light across your canopy, a few seconds per plant.
- Repeat daily, from the first day of flower through harvest.
For airborne spore pressure, the CleanLight Air runs 24/7 and continuously disinfects the air in rooms up to 100 m³.
Frequently asked questions
Is UV-C safe for the plants?
Used as directed, a slow pass of a few seconds per plant from the distance in the manual, UV-C does not harm cannabis or other crops. Overexposure can bleach leaf tips on the leaves closest to the lamp; if you see that, increase the distance or shorten the pass.
Is UV-C safe for me?
UV-C is harmful to skin and eyes, so you treat with yourself out of the beam. Every handheld unit ships with safety glasses and gloves, and the reflector shields you from direct exposure. The CleanLight Air keeps its lamp inside the housing, so it runs in an occupied room.
How often do I need to treat?
Daily. Powdery mildew and botrytis spores germinate every 24 to 48 hours, so a daily pass breaks the cycle. During an active outbreak, twice a day until symptoms subside.
How long does a UV-C lamp last?
The Pro lamp is rated for 9,000 hours, the Hobby lamp for 8,000 hours. Output fades with age before the lamp visibly fails, so we advise replacing handheld lamps every two years regardless of hours, and the Air lamp every 12 months under continuous use. Replacement lamps are in the Replacement Products collection.