ChloroKlean BPR Compliant Chlorine Dioxide Disinfectant - UK Supplier

Chlorine Dioxide vs PHMB for Pools and Spas

Chlorine dioxide (ClO₂) and PHMB (polyhexamethylene biguanide, sold under brands such as Baquacil and Soft Swim) are both used as primary pool and spa sanitisers, but they work on very different principles. PHMB is a polymeric biguanide biocide that disrupts microbial cell membranes; it is non-oxidising, so it cannot remove organic matter, body oils, or sun cream from pool water. PHMB must be paired with a hydrogen peroxide oxidiser shock, cannot be combined with chlorine or bromine, forms cloudy precipitates with sulphate-based pH adjusters and some calcium chemistries, and has limited published efficacy data against Legionella pneumophila. Chlorine dioxide is a strong selective oxidiser that destroys organics, penetrates biofilm, achieves >4-log Legionella reduction at 0.1-0.5 ppm residual, works across pH 4-10, and is fully BPR PT2-compliant. For UK pools and spas under HSG282 and PWTAG guidance, ClO₂ is the more capable choice. ChloroKlean Plus L20 is BPR-compliant for PT2 pool and spa applications.

Author
Key Advantage of ClO₂
Oxidises organics and penetrates biofilm; PHMB does neither. Documented Legionella efficacy; PHMB does not have comparable Legionella evidence.
By-products
ClO₂ produces no THMs or chloramines at typical doses. PHMB does not form THMs but creates cloudy precipitates with sulphates and calcium scale, and degrades into less-characterised polymer fragments.
pH Range
ClO₂ effective at pH 4-10. PHMB effective pH 6.5-7.8; outside this range biocidal activity drops sharply.
Regulatory Sources
HSE HSG282, PWTAG Pool Water Standards, EU BPR 528/2012 PT2, WHO Drinking-water Guidelines
UK Compliance
Both PHMB and chlorine dioxide require PT2 BPR authorisation for pool and spa use. ChloroKlean Plus L20 holds full BPR PT2 compliance.
Comparison Guide

Chlorine Dioxide vs PHMB

PHMB (polyhexamethylene biguanide) is marketed as a chlorine-free pool sanitiser. It is non-oxidising, incompatible with chlorine and bromine, forms cloudy precipitates with sulphates, and has limited documented Legionella efficacy. ClO₂ delivers stronger, BPR-compliant disinfection.

ClO₂

Chlorine Dioxide

  • Strong oxidiser - destroys body oils, sun cream, organics
  • Documented Legionella efficacy (>4-log reduction)
  • Penetrates biofilm in pool circulation pipework
  • Works pH 4-10 with no precipitation issues
  • Easy residual measurement via DPD or test strips
PHMB

PHMB (Polyhexamethylene Biguanide)

  • Non-irritating to eyes at correct dose
  • Stable at high temperatures in spas
  • Non-oxidising - cannot remove organic load
  • Cannot be combined with chlorine or bromine
  • Forms cloudy precipitates with sulphates

Detailed Comparison

Detailed comparison of chlorine dioxide versus phmb
FeatureChlorine DioxidePHMB
Oxidising Action

Strong

Destroys organics, body oils, sun cream

None

Requires separate H₂O₂ shock dosing

Biofilm Penetration

Excellent

Diffuses into pipework biofilm

Limited

Surface action; little EPS penetration

Legionella Efficacy

Proven (>4-log)

BS EN 13623:2020 verified

Limited data

Few peer-reviewed Legionella studies

pH Range

pH 4-10

Activity independent of pH

pH 6.5-7.8

Narrow optimum; drops outside range

Compatibility with Cl/Br

N/A primary

Used as primary biocide

Incompatible

Forms precipitates with chlorine or bromine

Sulphate / Calcium Compatibility

Good

No cloudy precipitates

Poor

Forms haze with sulphate pH adjusters

Cost per swimmer-day

Moderate

Sub-ppm dosing

High

Higher chemical cost; needs H₂O₂ shock

Residual Measurement

Simple

DPD test strips, electronic ClO₂ meter

Specialist test

PHMB-specific test kits required

BPR PT2 Status

Compliant

Full UK GB BPR PT2 authorisation

Compliant

Also approved active substance under PT2

When to Choose Each

Choose Chlorine Dioxide When:

  • You need oxidising power against body oils, sun cream, and organics
  • Legionella risk assessment requires documented biocide efficacy
  • Biofilm in pool circulation pipework needs removal
  • Water source contains sulphate alkalinity (most UK supplies)
  • Simple DPD residual measurement is preferred for operators
  • Cost per swimmer-day is a procurement criterion

Consider PHMB When:

  • Domestic outdoor pool with very low bather load
  • Operator strongly prefers a non-chlorine system on chemistry grounds
  • Pool sealants or finishes are chlorine-sensitive
  • Existing PHMB system is performing satisfactorily
  • Local water has very low sulphate alkalinity to avoid precipitation
"PHMB has a niche - quiet, private outdoor pools with low bather load and an owner who actively dislikes chlorine. Beyond that, it becomes hard to recommend. It does not oxidise organic load, it is incompatible with the most common pH adjusters, and the published Legionella evidence base is thin compared with chlorine dioxide. For any commercial pool or spa where HSG282 risk assessment is in scope, we'd specify ClO₂ every time."
GO

Gavin Owen, Managing Director, ChloroKlean

BPR-compliant disinfection specialist

Why Choose ChloroKlean Plus L20

If you're considering switching to chlorine dioxide, ChloroKlean Plus L20 is purpose-built for industrial and commercial applications.

BPR PT2 Compliant

ChloroKlean Plus L20 holds full UK GB BPR PT2 compliance for swimming pool, spa, and public area disinfection. Direct alternative to PHMB systems.

Oxidises and Sanitises

Single-product programme - no separate H₂O₂ shock dosing required. ClO₂ both oxidises organic load and provides residual biocidal action at sub-ppm doses.

Documented Legionella Efficacy

BS EN 13623:2020 testing confirms >4-log reduction of Legionella pneumophila. Field-proven in leisure facility spa systems where PHMB had failed risk-assessment audits.

Regulatory and Scientific References

This comparison is informed by the following authoritative sources. Always refer to the latest published guidance.

HSE HSG282
Health and Safety Executive (HSE)

Control of legionella and other infectious agents in spa-pool systems

HSG282 sets out the HSE's guidance on Legionella and other risks in spa pools. It expects biocides with documented Legionella efficacy - a key area where PHMB data is limited.

View source
PWTAG Guidance
Pool Water Treatment Advisory Group (PWTAG)

Swimming Pool Water Treatment and Quality Standards

PWTAG covers approved biocides for UK pools and spas, including PHMB and chlorine dioxide. PWTAG technical notes describe PHMB's incompatibilities and the limits of non-oxidising biocides.

View source
EU BPR PT2
European Chemicals Agency (ECHA)

Biocidal Products Regulation - Product Type 2 (Disinfectants for Private and Public Health)

PT2 covers disinfectants for swimming pools, spas, and similar public-area applications. Both PHMB and chlorine dioxide are approved active substances.

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WHO Guidelines
World Health Organization (WHO)

Guidelines for safe recreational water environments - Volume 2 (Swimming Pools and Similar Environments)

WHO recreational water guidelines emphasise biocide selection that combines biocidal action with oxidation of swimmer-introduced contaminants, where PHMB has documented limitations.

View source
ECHA PHMB Dossier
European Chemicals Agency (ECHA)

PHMB Biocidal Active Substance Assessment Report

ECHA assessment reports document PHMB's mechanism, efficacy, and identified hazards including PHMB's classification under CLP and limitations of efficacy data outside its optimal pH range.

View source

Frequently Asked Questions

Move From PHMB to Documented Pool Compliance

ChloroKlean Plus L20 delivers BPR PT2-compliant chlorine dioxide for pools and spas - with documented Legionella efficacy and no separate shock dosing required.