Pool & spa
Baquacil Pool Sanitiser & Algicide dupe
Why pay around £39.99 for Baquacil? The bulk active is PHMB solution (polyhexanide 20%, pool grade) — 62% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Baquacil Pool Sanitiser & Algicide
1 litre bottle · £39.99 typical snapshot
Water
2 · Active
PHMB (polyhexamethylene biguanide, 20%)
20% on the label
32289-58-0(C8H17N5)n
Bulk PHMB solution (polyhexanide 20%, pool grade)
3 · Mix
Neat; initial 50 ml/m³; maintain 30–50 ppm residual
£12.00 per working litre · 62% less than the shelf pack
- Active
- PHMB (polyhexamethylene biguanide, 20%)
- CAS
- 32289-58-0
- Dupe
- PHMB solution (polyhexanide 20%, pool grade)
- Saving
- 62% / L
Saving is per litre of working-strength mix versus a typical pack price, not versus the DIY kit total. Shop prices move — always check the listing.
Label teardown
What the pack promises versus what the label chemistry actually is.
The marketing claim
“Chlorine-free pool sanitiser — no bleach smell, no red eyes”
The chemical reality
Baquacil sanitiser is 20% PHMB (polyhexanide, CAS 32289-58-0) in water. PHMB is a broad-spectrum polymeric biguanide used in contact lens solution, wound irrigation and industrial biocides. The pool trade charges a heavy premium per litre; the same molecule is available as a 20% pool-grade solution from aquatics distributors at roughly half the retail price per litre.
Active vs filler
20% PHMB (polyhexamethylene biguanide, 20%) · 80% carrier / filler — Water
- Typical retail
- £39.99
- 1 litre bottle
- Estimated active cost
- £12.00
- Scaled from bulk £59.99 / 5 litres
- Indicative markup
- 3.3×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 1 litre bottle pack of Baquacil Pool Sanitiser & Algicide typically retails around £39.99 in pool & spa. That is a UK shelf-price snapshot for the maths on this page — not a live shop quote or a manufacturer RRP. Listings, sizes and deals move. The marketing line is that you are buying a finished lifestyle product, not a weighed chemical.
On the pack: Chlorine-free pool sanitiser — no bleach smell, no red eyes; Works alongside the Baquacil oxidiser system; and Gentle enough for sensitive swimmers.
The catch: Baquacil sanitiser is 20% PHMB (polyhexanide, CAS 32289-58-0) in water. PHMB is a broad-spectrum polymeric biguanide used in contact lens solution, wound irrigation and industrial biocides. The pool trade charges a heavy premium per litre; the same molecule is available as a 20% pool-grade solution from aquatics distributors at roughly half the retail price per litre.
- “Chlorine-free pool sanitiser — no bleach smell, no red eyes”
- “Works alongside the Baquacil oxidiser system”
- “Gentle enough for sensitive swimmers”
Proprietary Blend & Dosage Breakdown
The labelled active is PHMB (polyhexamethylene biguanide, 20%) at 20%. Everything else in the pack is water.
At 20% active, most of what you pay for is carrier and packaging. The brand is selling convenience, fragrance and a label — not a uniquely potent molecule.
Branded working strength is whatever comes out of the bottle. The bulk alternative is 20% PHMB solution (polyhexanide 20%, pool grade), mixed to Neat; initial 50 ml/m³; maintain 30–50 ppm residual.
- Labelled active
- PHMB (polyhexamethylene biguanide, 20%)
- 20%
- Carrier
- Water
- Retail pack
- 1 litre bottle · £39.99
The Active Chemical Alternative (Dupe Stack)
The dupe stack is PHMB solution (polyhexanide 20%, pool grade) at 20% bulk. Indexed as CAS 32289-58-0, formula (C8H17N5)n. Buy it as 5 litres for around £59.99 from Amazon UK.
Working strength: Neat; initial 50 ml/m³; maintain 30–50 ppm residual. Indicative cost £12.00 per diluted litre — 62% below a typical branded pack on a per-litre basis, before you reuse leftover bulk.
Follow the mixing method and the supplier SDS. Wear the listed PPE. Do not mix incompatible oxidisers, acids or ammonia.
- Wear gloves and splash goggles — PHMB is a sensitiser after repeated skin contact. Avoid contamination of contact lenses.
- Initial dose for a fresh fill: add 50 ml per m³ of pool water to establish a 30–50 ppm residual. Distribute around the returns with the pump running.
- Maintenance dose: test weekly with a PHMB test strip. Top up at 5–10 ml per m³ to hold 30–50 ppm. Heavy bather load or high temperatures consume the residual faster.
- Do not shock with chlorine, MPS, or bleach. Use a hydrogen peroxide-based oxidiser designed for PHMB systems. Never store PHMB beside chlorine products.
- 5 litres at an initial 50 ml/m³ treats 100 m³ — 100 times the capacity of a 1 litre Baquacil bottle.
Dilution recipe
100,000 L pool / spa volume
Working strength Neat; initial 50 ml/m³; maintain 30–50 ppm residual. Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
5,000 millilitres
PHMB solution (polyhexanide 20%, pool grade)
Water
99,995 litres
Carrier / diluent
0% concentrate · 100% water by working volume (solids are dissolved into the water share).
Required PPE
Loading calculator…
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedBaquacil | Raw active dupeDupeStack |
|---|---|---|
| Product | Pool Sanitiser & AlgicideAmazon UK search — listing, not a confirmed seller | PHMB solution (polyhexanide 20%, pool grade) |
| Pack / unit | 1 litre bottle · £39.99 | 5 litres · £59.99 |
| Active | PHMB (polyhexamethylene biguanide, 20%) at 20%Carrier: Water | 20% bulk(C8H17N5)n |
| CAS number | Not disclosed on pack | 32289-58-0 |
| Working strength | Ready-to-use pack | Dilute Neat; initial 50 ml/m³; maintain 30–50 ppm residual |
| Cost per litre | £39.99 / L typical pack | £12.00 / L mixed from bulk |
| Headline saving | Baseline | 62% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene)Eye protection. Indirect-vent splash goggles — not ordinary spectacles |
Active ingredient and cheaper alternative — FAQ
Can I mix PHMB with chlorine or MPS?
No — PHMB is incompatible with chlorine and most oxidisers. Chlorine deactivates PHMB by oxidising the biguanide chain. You cannot run a hybrid PHMB/chlorine pool: choose one system and convert fully. The Baquacil system pairs PHMB sanitiser with a dedicated hydrogen-peroxide oxidiser, not MPS or dichlor.
Does PHMB affect pool pH?
PHMB has little direct effect on pH. Maintain pH 7.2–7.6 as normal using soda ash or dry acid. PHMB does not produce chloramine-type combined residuals, so the main pH driver in a biguanide pool is bather load and water chemistry.
How do you mix the Pool Sanitiser & Algicide dupe stack?
Wear gloves and splash goggles — PHMB is a sensitiser after repeated skin contact. Avoid contamination of contact lenses. Initial dose for a fresh fill: add 50 ml per m³ of pool water to establish a 30–50 ppm residual. Distribute around the returns with the pump running. Maintenance dose: test weekly with a PHMB test strip. Top up at 5–10 ml per m³ to hold 30–50 ppm. Heavy bather load or high temperatures consume the residual faster. Do not shock with chlorine, MPS, or bleach. Use a hydrogen peroxide-based oxidiser designed for PHMB systems. Never store PHMB beside chlorine products. 5 litres at an initial 50 ml/m³ treats 100 m³ — 100 times the capacity of a 1 litre Baquacil bottle.
DupeStack provides chemical concentration data and educational mixing guides only. Wellness pages compare food supplements, not medicines or prescribed treatments. Always review the supplier Safety Data Sheet (SDS) and comply with UK Health and Safety Executive (HSE) and COSHH regulations when handling concentrated substances. Mixing and storage are at your own risk. Some links are affiliate advertisements (Amazon Associates, eBay Partner Network, and Awin when those programmes are live). Commissions do not change listed concentrations or calculator output.
Related guides
Pool guide
PHMB and bromine pool care: chlorine-free sanitising decoded
How polyhexanide (PHMB) and sodium bromide work as chlorine-free pool sanitisers — activation chemistry, compatibility rules, and links to DupeStack teardowns.
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Pool and spa basics: pH, chlorine and cyanuric acid without the brand kit
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Pool guide
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- Retail pack
- £11.501 kg bottle
- Raw active
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- Retail pack
- £9.991.5 kg
- Raw active
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- Retail pack
- £42.005 kg
- Raw active
- TCCA 90% chlorine tablets (200 g)87-90-1
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£75.00Save 62% / L
Indicative DIY stack