Consumer advocacy teardown
Hardness Plus (Calcium Increaser) alternative & active ingredient dupe
Stop paying £13.99 for Fi-Clor. The bulk active is Calcium chloride flakes (77–80% technical grade) — 94% less per working litre than a typical pack.
- Active
- Calcium chloride anhydrous / dihydrate
- CAS
- 10043-52-4
- Dupe
- Calcium chloride flakes (77–80% technical grade)
- Saving
- 94% / 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 1 kg bottle pack of Fi-Clor Hardness Plus (Calcium Increaser) is about £13.99 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: Eliminates soft-water foam and surface etching; and Extends pool shell and heater element lifespan.
The catch: Repackaged de-icing and industrial desiccating salt marked up tenfold.
- “Eliminates soft-water foam and surface etching”
- “Extends pool shell and heater element lifespan”
Proprietary Blend & Dosage Breakdown
The labelled active is Calcium chloride anhydrous / dihydrate at 77%. Everything else in the pack is mineral binders.
Even when the pack is sold as “pure” or ready-to-use, the dose that actually does the work is Calcium chloride anhydrous / dihydrate. 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 80% Calcium chloride flakes (77–80% technical grade), mixed to 15 g per 1,000 L raises calcium hardness by 10 ppm.
- Labelled active
- Calcium chloride anhydrous / dihydrate
- 77%
- Carrier
- Mineral binders
- Retail pack
- 1 kg bottle · £13.99
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Calcium chloride flakes (77–80% technical grade) at 80% bulk. Indexed as CAS 10043-52-4, formula CaCl2. Buy it as 25 kg sack for about £21.00 from Amazon UK.
Working strength: 15 g per 1,000 L raises calcium hardness by 10 ppm. Indicative cost £0.84 per diluted litre — 94% 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.
- Pre-dissolve flakes thoroughly in cold water (the dissolution reaction produces heat).
- Add in small increments with the circulation pump active to avoid local clouding.
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 chloride flakes (77–80% technical grade)
- Concentrate
- 15 g
- grams of solid
- Water
- 1,000 L
- carrier volume
- Batch cost
- £0.01
- 1,000 L working solution
- Saved vs retail
- £0.20
- 94% · retail £0.21
Estimated coverage at the listed rate: 0.8 m².
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedFi-Clor | Raw active dupeDupeStack |
|---|---|---|
| Product | Hardness Plus (Calcium Increaser)Amazon UK search — listing, not a confirmed seller | Calcium chloride flakes (77–80% technical grade) |
| Pack / unit | 1 kg bottle · £13.99 | 25 kg sack · £21.00 |
| Active | Calcium chloride anhydrous / dihydrate at 77%Carrier: Mineral binders | 80% bulkCaCl2 |
| CAS number | Not disclosed on pack | 10043-52-4 |
| Working strength | Ready-to-use pack | Dilute 15 g per 1,000 L raises calcium hardness by 10 ppm |
| Cost per litre | £13.99 / pack | £0.84 / L mixed from bulk |
| Headline saving | Baseline | 94% 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
What is the active ingredient in Fi-Clor?
Fi-Clor Hardness Plus (Calcium Increaser) is labelled as Calcium chloride anhydrous / dihydrate at 77%. The carrier is Mineral binders. Pack size: 1 kg bottle. The bulk equivalent we index is Calcium chloride flakes (77–80% technical grade) (CAS 10043-52-4).
Is Calcium chloride flakes (77–80% technical grade) safe on the intended surface?
Used at the listed working strength (15 g per 1,000 L raises calcium hardness by 10 ppm), 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 Hardness Plus (Calcium Increaser)?
Yes. The bulk equivalent is Calcium chloride flakes (77–80% technical grade) (CAS 10043-52-4). Indicative saving 94% per working litre versus a typical £13.99 pack. Working strength: 15 g per 1,000 L raises calcium hardness by 10 ppm. Live shop prices move.
How do you mix the Hardness Plus (Calcium Increaser) dupe stack?
Pre-dissolve flakes thoroughly in cold water (the dissolution reaction produces heat). Add in small increments with the circulation pump active to avoid local clouding.
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.
More teardowns
Pool & spa
Clearwater pH Plus Spa / Pool Balancer
Clearwater
- Retail pack
- £11.501 kg bottle
- Raw active
- Dense soda ash (sodium carbonate 99%)497-19-8
pH Plus is dense soda ash — 99% sodium carbonate, CAS 497-19-8. Pool-shop packaging turns a £2.70/kg commodity into an £11.50/kg ritual.
Pool & spa
Clearwater pH Minus
Clearwater
- Retail pack
- £9.991.5 kg
- Raw active
- Sodium bisulphate (dry acid)7681-38-1
pH Minus is dry acid — sodium bisulphate. Pool retail is a small tub; chemical suppliers sell it in 5 kg lots for a third of the per-kilo price.
Pool & spa
Clearwater Multifunction Chlorine Tablets
Clearwater
- Retail pack
- £42.005 kg
- Raw active
- TCCA 90% chlorine tablets (200 g)87-90-1
The tablet is 90% TCCA — the same stabilised chlorine used in bulk 200 g pucks. ‘Multifunction’ is a pinch of clarifier and a lot of packaging. Buy TCCA, dose from an SDS, and keep cyanuric acid in range.
DIY stack · 94% / L vs branded
£32.50indicative kit · Amazon cannot add a mixed search kit as one basket