Frequently Asked Questions

Everything growers ask before buying CleanLight. Can't find your question? Email hello@pureuv.nl — we reply within one business day.

Effectiveness — what does CleanLight actually do?

What does CleanLight kill?

CleanLight uses UV-C light at 254nm to destroy the DNA of microorganisms on contact. It's effective against:

• Powdery mildew — both preventative and curative; kills on contact and breaks the spore reproduction cycle
• Botrytis / bud rot — preventative and curative on the surface; cannot cure fungus that has already grown deep into the plant tissue
• Fusarium and other surface fungi — once visible above the soil line, CleanLight kills it on the plant surface and stops further spread
• Bacteria and viruses on plant surfaces
• Mites, aphids, and other insects — research is available showing CleanLight's effectiveness as part of an integrated pest management approach; ask us if you'd like to see the studies

Does it work as a curative or only as a preventative?

Powdery mildew is the pathogen CleanLight can fully cure on the plant. For botrytis, fusarium, bacteria, and viruses, CleanLight works primarily as a preventative — it stops cross-contamination and prevents further spread by destroying surface pathogens before they reach healthy tissue or neighbouring plants.

How quickly will I see results?

Most growers see visible powdery mildew reduction within 3–7 days of daily treatment. The "Great product, after 4 days I already saw the powdery mildew disappear" review on the Pro page is typical for a moderate outbreak treated promptly.

Is there scientific evidence?

Yes. UV-C at 254nm has been used for decades in hospitals, water treatment, and food production to deactivate pathogens. CleanLight has been in the agriculture market since 2006 and is used by growers in 40+ countries. The mechanism (UV-C disrupting microbial DNA) is well-established and not specific to CleanLight — what's specific is the parabolic reflector design that delivers a calibrated dose without harming the plant.

Usage — how and how often to treat

How often should I treat my plants?

For prevention: daily passes are ideal — powdery mildew and botrytis spores germinate every 24–48 hours, so daily treatment breaks the cycle.

For active outbreaks: preferably twice a day until symptoms subside, then switch back to a daily preventative schedule.

We recommend daily treatment as a minimum across all units — less frequent treatment leaves enough time for spores to re-establish between sessions.

How long do I treat each plant?

With the CleanLight Pro (36W): 5–10 seconds per plant.

With the CleanLight Hobby (11W): the Hobby runs about a third of the Pro's UV-C output, so plan for roughly 3× the exposure time — around 15–30 seconds per area, slightly longer for dense canopies.

For outdoor / open-air use: you can extend exposure further. Outdoor plants are more UV-tolerant, so longer per-spot exposure is safe.

Can I overdo it?

Yes — excessive UV-C can stress plants, especially young clones or genetics that are more UV-sensitive. Symptoms of overexposure are mild leaf burn or bleaching on the leaves closest to the lamp. If you see this, increase the distance, shorten exposure time, or reduce frequency. Plants typically recover within a few days.

Can I use it during flower?

Yes. CleanLight is safe to use from cuttings through post-harvest. Many commercial growers use it daily through flower because it leaves no residue and meets state cannabis testing requirements for chemical residues.

Should the unit warm up before use?

Yes — both the Hobby and Pro should warm up for about one minute before starting treatment. The lamp reaches full germicidal output once it's warm.

Choosing the right unit

What's the difference between the Hobby and the Pro?

The Hobby runs an 11W lamp — ideal for home growers with a few plants in a tent. The Pro runs a 36W lamp with over 3× the UV-C output, covering more canopy per sweep and significantly cutting daily treatment time. If you're running a dedicated grow room, multiple tents, or commercial production, the Pro is built for that scale.

Full comparison: Which CleanLight is right for your grow?

When do I need the CleanLight Air?

The Air is recommended for any indoor grow because it tackles a different problem than the Hobby and Pro: airborne spore pressure. Powdery mildew and botrytis spores travel through the air and re-infect plants continuously. Treating the canopy with a Hobby or Pro handles spores on the plant; the Air handles spores in the air. Many serious growers run both.

How big a room does the Air cover?

The Air is rated for rooms up to 100 m³ (about 3,500 cubic feet — roughly 437 square feet with an 8-foot ceiling). It also works in smaller rooms — there's no minimum.

For rooms larger than 100 m³, growers typically install multiple units on opposite sides of the room. Contact us if you're planning a commercial install — we can spec the right configuration.

Can I use CleanLight outdoors?

Yes. The Hobby and Pro both work outdoors. Outdoor plants are typically more UV-tolerant, so you can extend per-spot exposure. The Air is for indoor / enclosed spaces only — it cleans air inside a sealed room.

Maintenance — bulbs and filters

How long do the UV-C lamps last?

• CleanLight Hobby lamp: 8,000 hours — replace every 2 years regardless of usage
• CleanLight Pro lamp: 9,000 hours — replace every 2 years regardless of usage
• CleanLight Air lamp: 9,000 hours — replace every 12 months with continuous use

UV-C lamps don't burn out dramatically — they fade. Output drops below the germicidal threshold long before the lamp visibly fails, which is why we recommend replacement on the schedule above even if the lamp still appears to work.

Browse replacement bulbs and filters: Replacement products

Does the CleanLight Air filter need replacing?

Yes. The High Air Flow filter should be replaced annually with continuous use, or sooner if it visibly clogs. Buy a replacement Air filter →

Safety

Is UV-C safe for plants?

Yes — at the dose CleanLight delivers, used correctly. The parabolic reflector is specifically calibrated to deliver a UV-C dose that destroys surface pathogens without damaging plant tissue. Some genetics are slightly more UV-sensitive than others — if you see leaf burn, increase distance and reduce exposure.

Is UV-C safe for me?

UV-C is harmful to skin and eyes with direct, prolonged exposure. CleanLight ships every Hobby and Pro unit with safety glasses and gloves — wear them during treatment. The parabolic reflector directs the UV downward toward the canopy and shields the operator from direct exposure.

The CleanLight Air is fully enclosed — the UV-C lamp is inside the unit and never reaches occupants. It's safe to run continuously in occupied rooms.

Does CleanLight harm beneficial insects?

No. The brief, low-dose UV-C exposure used in crop treatment is not harmful to natural pest control insects (ladybugs, predatory mites, etc.). Many of our customers combine CleanLight with biological pest control.

Is a license required to use CleanLight?

No. CleanLight is sold as a UV-C device, not a registered pesticide. No license, certification, or permit is required to use it on any crop, including cannabis.

Buying, shipping, returns

Where do you ship from?

All orders ship from our warehouse in Veenendaal, the Netherlands, via FedEx or DHL. Most orders arrive in 1–3 business days.

How much is shipping?

Free on orders over $150 USD. Below that, shipping is calculated at checkout based on your delivery address.

Do you ship to my country?

We ship to most countries worldwide. If your address doesn't show a shipping option at checkout, email hello@pureuv.nl — we can usually arrange it.

What's your return policy?

15 days from delivery for unused units in original packaging. Defective-on-arrival units are replaced at our cost. Full policy: Shipping & Returns

What about warranty?

2-year manufacturer warranty on every CleanLight unit. Lamps and filters are consumables and not covered — see the spec sheet on each product page for expected lifespan.

How do I contact you?

Email hello@pureuv.nl — we reply within one business day. For commercial or large-scale installations, mention "commercial inquiry" in the subject and we'll route accordingly.