Pool & spa
Fi-Clor Multi-Functional Algicide dupe
Why pay around £36.99 for Fi-Clor? The bulk active is Sodium bromide (bromine bank activating salt) — 50% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Fi-Clor Multi-Functional Algicide
3 litres · £36.99 typical snapshot
Water and etidronic acid (HEDP); SDS water about 70%
2 · Active
Polymerised quaternary ammonium (polyquat)
20% on the label
7647-15-6NaBr
Bulk Sodium bromide (bromine bank activating salt)
3 · Mix
Neat season dose: 1.5 litres per 50,000 litres (about 30 ml/m³)
£6.20 per working litre · 50% less than the shelf pack
- Active
- Polymerised quaternary ammonium (polyquat)
- CAS
- 7647-15-6
- Dupe
- Sodium bromide (bromine bank activating salt)
- Saving
- 50% / 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
“Copper-free long-life algicide”
The chemical reality
Copper-free pool algicide is a polymeric quat, not copper sulphate and not BAC. The Fi-Clor SDS lists polymerised quaternary ammonium (CAS 25988-97-0) at 10–25%, plus etidronic acid (CAS 2809-21-4) at 2.5–10%. A 3 litre bottle is about £37. A 5 litre trade jerry of polyquat algaecide is about £31 — roughly half the price per litre, if the jerry’s SDS is in the same strength band.
Active vs filler
20% Polymerised quaternary ammonium (polyquat) · 80% carrier / filler — Water and etidronic acid (HEDP); SDS water about 70%
- Typical retail
- £36.99
- 3 litres
- Estimated active cost
- £18.59
- Scaled from bulk £30.99 / 5 litres
- Indicative markup
- 2.0×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 3 litres pack of Fi-Clor Multi-Functional Algicide typically retails around £36.99 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: Copper-free long-life algicide; Also sold as a clarifier, anti-stain and anti-scale; and Season dose alongside a chlorine sanitiser.
The catch: Copper-free pool algicide is a polymeric quat, not copper sulphate and not BAC. The Fi-Clor SDS lists polymerised quaternary ammonium (CAS 25988-97-0) at 10–25%, plus etidronic acid (CAS 2809-21-4) at 2.5–10%. A 3 litre bottle is about £37. A 5 litre trade jerry of polyquat algaecide is about £31 — roughly half the price per litre, if the jerry’s SDS is in the same strength band.
- “Copper-free long-life algicide”
- “Also sold as a clarifier, anti-stain and anti-scale”
- “Season dose alongside a chlorine sanitiser”
Proprietary Blend & Dosage Breakdown
The labelled active is Polymerised quaternary ammonium (polyquat) at 20%. Everything else in the pack is water and etidronic acid (hedp); sds water about 70%.
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% Sodium bromide (bromine bank activating salt), mixed to Neat season dose: 1.5 litres per 50,000 litres (about 30 ml/m³).
- Labelled active
- Polymerised quaternary ammonium (polyquat)
- 20%
- Carrier
- Water and etidronic acid (HEDP); SDS water about 70%
- Retail pack
- 3 litres · £36.99
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Sodium bromide (bromine bank activating salt) at 20% bulk. Indexed as CAS 7647-15-6, formula NaBr. Buy it as 5 litres for around £30.99 from Amazon UK.
Working strength: Neat season dose: 1.5 litres per 50,000 litres (about 30 ml/m³). Indicative cost £6.20 per diluted litre — 50% 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.
- Corrosive concentrate (the Fi-Clor SDS is strongly acidic). Gloves, goggles and old clothes. Very toxic to aquatic life — keep the neat liquid out of ditches. The label warns that mixing with other products may release chlorine gas. Never combine it with acid, cal-hypo or dichlor in a bucket.
- A sanitiser still has to be in range. This is not a shock and not a disinfectant residual. Fi-Clor’s published season rate is 1.5 litres per 50,000 litres (about 11,000 gallons) every six months — about 30 ml per cubic metre.
- Brush and vacuum first. Dilute the measured dose into a plastic bucket of pool water, then pour near a return with the pump running. Do not swim until the water is mixed and the sanitiser tests in range.
- Swimming Pool Chemicals lists a 5 litre polyquat algaecide at £30.99, against about £12.30 a litre for the 3 litre Fi-Clor bottle (£36.99). Their treatment line is 1 litre per 10,000 gallons — similar order, not a 1:1 swap. Read the jerry. A 50–60% technical polyquat is a different dilution; do not pour it at the Fi-Clor rate.
- The HEDP in Fi-Clor is a sequestrant, not the algicide. Copper stains and polyquat are different tools. One chemistry per addition.
Dilution recipe
50,000 L pool / spa volume
Working strength Neat season dose: 1.5 litres per 50,000 litres (about 30 ml/m³). Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
1,500 millilitres
Sodium bromide (bromine bank activating salt)
Water
49,998.5 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 brandedFi-Clor | Raw active dupeDupeStack |
|---|---|---|
| Product | Multi-Functional AlgicideAmazon UK search — listing, not a confirmed seller | Sodium bromide (bromine bank activating salt) |
| Pack / unit | 3 litres · £36.99 | 5 litres · £30.99 |
| Active | Polymerised quaternary ammonium (polyquat) at 20%Carrier: Water and etidronic acid (HEDP); SDS water about 70% | 20% bulkNaBr |
| CAS number | Not disclosed on pack | 7647-15-6 |
| Working strength | Ready-to-use pack | Dilute Neat season dose: 1.5 litres per 50,000 litres (about 30 ml/m³) |
| Cost per litre | £12.33 / L typical pack | £6.20 / L mixed from bulk |
| Headline saving | Baseline | 50% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene)Eye protection. Indirect-vent splash goggles — not ordinary spectaclesAcid-resistant PPE. Apron and gloves rated for corrosive liquids |
Active ingredient and cheaper alternative — FAQ
Is this the same as Lo-Chlor copper algaecide?
No. Lo-Chlor copper is copper sulphate pentahydrate (CAS 7758-98-7), a metal residual that can stain plaster and hair. This bottle is a polymeric quaternary ammonium (CAS 25988-97-0) with some HEDP. No copper. Do not stack the two because both say algicide.
Does the HEDP in the bottle replace a scale inhibitor?
Only in part. Etidronic acid here is 2.5–10%, beside the polyquat. Lo-Chlor No More Scale is an HEDP sequestrant sold for that job (CAS 2809-21-4). Do not treat a season dose of algicide as a full scale-control programme, and do not mix the neat liquids.
How do you mix the Multi-Functional Algicide dupe stack?
Corrosive concentrate (the Fi-Clor SDS is strongly acidic). Gloves, goggles and old clothes. Very toxic to aquatic life — keep the neat liquid out of ditches. The label warns that mixing with other products may release chlorine gas. Never combine it with acid, cal-hypo or dichlor in a bucket. A sanitiser still has to be in range. This is not a shock and not a disinfectant residual. Fi-Clor’s published season rate is 1.5 litres per 50,000 litres (about 11,000 gallons) every six months — about 30 ml per cubic metre. Brush and vacuum first. Dilute the measured dose into a plastic bucket of pool water, then pour near a return with the pump running. Do not swim until the water is mixed and the sanitiser tests in range. Swimming Pool Chemicals lists a 5 litre polyquat algaecide at £30.99, against about £12.30 a litre for the 3 litre Fi-Clor bottle (£36.99). Their treatment line is 1 litre per 10,000 gallons — similar order, not a 1:1 swap. Read the jerry. A 50–60% technical polyquat is a different dilution; do not pour it at the Fi-Clor rate. The HEDP in Fi-Clor is a sequestrant, not the algicide. Copper stains and polyquat are different tools. One chemistry per addition.
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.
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£45.00Save 50% / L
Indicative DIY stack