Pool & spa
Fi-Clor Hardness Plus (Calcium Increaser) dupe
Why pay around £13.99 for Fi-Clor? The bulk active is Calcium chloride flakes (77–80% technical grade) — 94% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Fi-Clor Hardness Plus (Calcium Increaser)
1 kg bottle · £13.99 typical snapshot
Mineral binders
2 · Active
Calcium chloride anhydrous / dihydrate
77% on the label
10043-52-4CaCl2
Bulk Calcium chloride flakes (77–80% technical grade)
3 · Mix
15 g per 1,000 L raises calcium hardness by 10 ppm
£0.84 per working litre · 94% less than the shelf 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.
Label teardown
What the pack promises versus what the label chemistry actually is.
The marketing claim
“Eliminates soft-water foam and surface etching”
The chemical reality
Repackaged de-icing and industrial desiccating salt marked up tenfold.
Active vs filler
77% Calcium chloride anhydrous / dihydrate · 23% carrier / filler — Mineral binders
- Typical retail
- £13.99
- 1 kg bottle
- Estimated active cost
- £0.81
- Scaled from bulk £21.00 / 25 kg sack
- Indicative markup
- 17.3×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 1 kg bottle pack of Fi-Clor Hardness Plus (Calcium Increaser) typically retails around £13.99 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: 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 around £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.
Dilution recipe
1,000 L pool / spa volume
Working strength 15 g per 1,000 L raises calcium hardness by 10 ppm. Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
15 grams
Calcium chloride flakes (77–80% technical grade)
Water
1,000 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 | 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 pack that typically retails around £13.99. 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 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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Indicative DIY stack