Consumer advocacy teardown
Superfast Shock Chlorine Granules alternative & active ingredient dupe
Stop paying £34.00 for Fi-Clor. The bulk active is Calcium hypochlorite granules 65–70% — 62% less per working litre than a typical pack.
- Active
- Calcium hypochlorite
- CAS
- 7778-54-3
- Dupe
- Calcium hypochlorite granules 65–70%
- 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.
The Marketing Claim & The Catch
A typical 2.5 kg tub pack of Fi-Clor Superfast Shock Chlorine Granules is about £34.00 in pool & spa. That is a snapshot, not a live Amazon price — listings, sizes and deals move. The marketing line is that you are buying a finished lifestyle product, not a weighed chemical.
On the pack: Unstabilised shock — fast dissolve, no extra CYA; and Ideal for indoor pools and a weekly oxidising shock.
The catch: This is not TCCA and it is not bottle bleach. Cal-hypo is the same oxidiser sold to commercial pools in 5–10 kg kegs. A 2.5 kg spa tub is a small pour from that keg.
- “Unstabilised shock — fast dissolve, no extra CYA”
- “Ideal for indoor pools and a weekly oxidising shock”
Proprietary Blend & Dosage Breakdown
The labelled active is Calcium hypochlorite at 70%. Everything else in the pack is stabilisers and anti-caking salts.
Even when the pack is sold as “pure” or ready-to-use, the dose that actually does the work is Calcium hypochlorite. The rest is how they get it into a bottle you will pick up.
Branded working strength is whatever comes out of the bottle. The bulk alternative is 70% Calcium hypochlorite granules 65–70%, mixed to 0.01 g/L (10 g/m³ for ~7 ppm free chlorine).
- Labelled active
- Calcium hypochlorite
- 70%
- Carrier
- Stabilisers and anti-caking salts
- Retail pack
- 2.5 kg tub · £34.00
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Calcium hypochlorite granules 65–70% at 70% bulk. Indexed as CAS 7778-54-3, formula Ca(OCl)2. Buy it as 5 kg for about £26.00 from Amazon UK.
Working strength: 0.01 g/L (10 g/m³ for ~7 ppm free chlorine). Indicative cost £0.00 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.
- Oxidiser. Gloves, goggles, never mix with acids, TCCA or oil. Pre-dissolve in a plastic bucket of pool water, then distribute.
- About 10 g per m³ (10 g per 1,000 litres) raises free chlorine by roughly 7 ppm as a shock — test, do not guess.
- Cal-hypo raises hardness. It does not add cyanuric acid (unlike TCCA tablets). Store dry, away from acid and organics.
- 5 kg is two 2.5 kg branded tubs. Per kilo this is the cheaper pour.
Mixing desk
Dilution calculator
Switch between filling a sprayer and covering a measured surface. Figures are educational estimates from the listed ratio — always check the SDS.
Formula
Calcium hypochlorite granules 65–70%
- Concentrate
- 100 g
- grams of solid
- Water
- 10,000 L
- carrier volume
- Batch cost
- £0.52
- 10,000 L working solution
- Saved vs retail
- £0.84
- 62% · retail £1.36
Estimated coverage at the listed rate: 8.3 m².
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedFi-Clor | Raw active dupeDupeStack |
|---|---|---|
| Product | Superfast Shock Chlorine GranulesAmazon UK search — listing, not a confirmed seller | Calcium hypochlorite granules 65–70% |
| Pack / unit | 2.5 kg tub · £34.00 | 5 kg · £26.00 |
| Active | Calcium hypochlorite at 70%Carrier: Stabilisers and anti-caking salts | 70% bulkCa(OCl)2 |
| CAS number | Not disclosed on pack | 7778-54-3 |
| Working strength | Ready-to-use pack | Dilute 0.01 g/L (10 g/m³ for ~7 ppm free chlorine) |
| Cost per litre | £34.00 / pack | £0.00 / 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 spectaclesVentilation. Use outdoors or with mechanical extraction |
Active ingredient and cheaper alternative — FAQ
What is the active ingredient in Fi-Clor?
Fi-Clor Superfast Shock Chlorine Granules is labelled as Calcium hypochlorite at 70%. The carrier is Stabilisers and anti-caking salts. Pack size: 2.5 kg tub. The bulk equivalent we index is Calcium hypochlorite granules 65–70% (CAS 7778-54-3).
Is Calcium hypochlorite granules 65–70% safe on the intended surface?
Used at the listed working strength (0.01 g/L (10 g/m³ for ~7 ppm free chlorine)), the dupe is the same chemistry as the branded pack for pool and spa water once dosed from a test kit. That is not a blanket all-clear: read the supplier SDS, wear the listed PPE, keep acids away from hypochlorite, and follow UK HSE/COSHH rules. Wellness teardowns are supplements, not medicines.
Is there a cheaper alternative to Fi-Clor Superfast Shock Chlorine Granules?
Yes. The bulk equivalent is Calcium hypochlorite granules 65–70% (CAS 7778-54-3). Indicative saving 62% per working litre versus a typical £34.00 pack. Working strength: 0.01 g/L (10 g/m³ for ~7 ppm free chlorine). Live shop prices move.
How do you mix the Superfast Shock Chlorine Granules dupe stack?
Oxidiser. Gloves, goggles, never mix with acids, TCCA or oil. Pre-dissolve in a plastic bucket of pool water, then distribute. About 10 g per m³ (10 g per 1,000 litres) raises free chlorine by roughly 7 ppm as a shock — test, do not guess. Cal-hypo raises hardness. It does not add cyanuric acid (unlike TCCA tablets). Store dry, away from acid and organics. 5 kg is two 2.5 kg branded tubs. Per kilo this is the cheaper pour.
DupeStack provides chemical concentration data and educational mixing guides. Always review official manufacturer Safety Data Sheets (SDS) and comply with UK Health and Safety Executive (HSE) and COSHH regulations when handling concentrated substances. Some links on this site are affiliate links.
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£38.00indicative kit · Amazon cannot add a mixed search kit as one basket