Pythoff — Hydroponic Root Steriliser & Pythium Prevention for DWC & RDWC Systems
Best for: Growers running hydroponic systems who want reliable pythium and root-rot prevention without guesswork
Our thoughts
This is the steriliser serious hydroponic growers reach for when they've had root problems in the past — or want to make sure they never do. Non-systemic, stable for weeks, and it actually works. One bottle lasts an age, which tells you everything about concentration and value.
Root-rot can wipe out a hydroponic system in 2-4 days. Pythoff is a non-systemic hydroponic steriliser designed to keep your nutrient solution and root zone clean, treating and preventing pythium and other forms of root disease before they take hold. It's the kind of product that turns crop failure into crop security — especially in warm conditions or summer growing when pathogens thrive.
Unlike some sterilisers that degrade quickly, Pythoff stays active for roughly 7 days per dose, giving you a stable, trustworthy level of protection without constant redosing. It's been used by commercial growers (including operations running 50,000+ plants) for decades, and it has a track record that speaks for itself.
How it compares
Pythoff sits in the preventative steriliser category, positioned between aggressive shock treatments and microbial approaches.
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vs. Hydrogen peroxide: H2O2 works quickly but degrades within hours; Pythoff stays active for a week and won't damage beneficial inoculants if you use them separately
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vs. Beneficial bacteria (e.g. Hydroguard): Bacteria fight pathogens passively; Pythoff actively sterilises the entire system, making it better for existing infections or high-risk scenarios
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vs. Hypochlorous acid products: Similar sterilisation capability, but Pythoff is more stable in solution and has a longer active life — critical for consistent dosing accuracy
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Stability advantage: Pythoff PLUS is standardised to a specific concentration with 10+ year shelf-life. Most competitor products degrade rapidly, making dosing unreliable
Usage guidance
Pythoff works across DWC, RDWC, NFT, and drip systems. Dosing is straightforward but precision matters — underdosing won't protect you, overdosing harms roots.
Preventative dosing
Add 2ml per 10 litres of reservoir into 1 litre of nutrient-free water, mix well, then add slowly to your reservoir over 30 seconds while stirring. Run your pump for 15 minutes to distribute it fully. Redose every 7 days as routine maintenance.
Active treatment (existing root-rot)
If you've already got brown, slimy roots or early-stage disease, dose daily until the problem clears. Stop using organic additives during treatment — Pythoff works best in a clean system. Caught early enough, it can save your crop.
Sensitive plants or seedlings
Use half the stated dose for young plants or species that react badly to strong treatments.
Important compatibility notes
Pythoff is not compatible with hydrogen peroxide or beneficial bacteria products. Don't mix it with those. It's also unsuitable for living soils, coco-peat, or wood-chip substrates because it kills the beneficial microbes you need in those systems — this is a hydroponic product through and through.
Technical specifications
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Type: Non-systemic hydroponic steriliser / nutrient conditioner
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Active ingredient: Proprietary water treatment formulation (FlairForm, since 1966)
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Dose rate: 0.1–0.2 ml/L (0.4–0.8 ml/gallon)
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Preventative schedule: Redose every 7 days
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Treatment schedule: Daily dosing for active root-rot infections
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Active life in solution: Approximately 7 days
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Shelf-life (Pythoff PLUS): 10+ years (standardised concentration)
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System compatibility: DWC, RDWC, NFT, drip irrigation
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Not suitable for: Soil, coco-peat, wood-chip, or living substrate systems
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Safe from: Seed to harvest (non-systemic, organic-compliant)
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Secondary benefit: Helps prevent plumbing blockages in drippers, jets, and filters by conditioning nutrient solution
Who this is for
- RDWC and DWC operators looking for reliable pythium prevention
- Growers in warm climates or summer-growing regions (when root pathogens thrive)
- Commercial-scale operations where crop failure is costly
- Anyone who's had root-rot before and doesn't want it to happen again
- Hydroponic growers prioritising system security over minimal chemical intervention
- Operators running multiple reservoirs where stability and long active-life matter
Particularly well suited to growers who've learned the hard way that prevention is infinitely cheaper than recovery.
Our take
Pythoff is the steriliser that professional growers trust because it works reliably and stays active long enough to be worth using. It's not the cheapest option, but a bottle lasts an age — the concentration is serious, the stability is proven, and the results speak for themselves.
If you're running hydroponic systems and you've either had root problems or you're smart enough to avoid them, this is worth picking up. Peace of mind in a bottle, and one less thing to worry about on changeover day. Good time to grab it while clearance stock lasts.
