Household cleaning
Calgon 4-in-1 Limescale Protection Tablets dupe
Why pay around £10.50 for Calgon? The bulk active is Trisodium citrate dihydrate (food grade) — 70% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Calgon 4-in-1 Limescale Protection Tablets
390 grams (30 tablets) · £10.50 typical snapshot
Tablet binders, cellulose and perfume
2 · Active
Polycarboxylates (with sodium citrate in older tabs)
22% on the label
6132-04-3Na3C6H5O7·2H2O
Bulk Trisodium citrate dihydrate (food grade)
3 · Mix
10 g per wash in the detergent drawer (hardness sequester)
£0.09 per working litre · 70% less than the shelf pack
- Active
- Polycarboxylates (with sodium citrate in older tabs)
- CAS
- 6132-04-3
- Dupe
- Trisodium citrate dihydrate (food grade)
- Saving
- 70% / 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
“Limescale prevention with every wash”
The chemical reality
Current Calgon 4-in-1 tabs declare 15–30% polycarboxylates (sodium polyacrylate family, CAS 9003-04-7) plus perfume. Older Express tabs also listed sodium citrate. The everyday hardness job is a teaspoon of food-grade trisodium citrate — not a monthly citric drum descale (that is Service-it).
Active vs filler
22% Polycarboxylates (with sodium citrate in older tabs) · 78% carrier / filler — Tablet binders, cellulose and perfume
- Typical retail
- £10.50
- 390 grams (30 tablets)
- Estimated active cost
- £0.82
- Scaled from bulk £9.49 / 1 kg
- Indicative markup
- 12.8×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 390 grams (30 tablets) pack of Calgon 4-in-1 Limescale Protection Tablets typically retails around £10.50 in household cleaning. 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: Limescale prevention with every wash; Removes dirt residue, odours and rust; and Helps your washing machine live longer.
The catch: Current Calgon 4-in-1 tabs declare 15–30% polycarboxylates (sodium polyacrylate family, CAS 9003-04-7) plus perfume. Older Express tabs also listed sodium citrate. The everyday hardness job is a teaspoon of food-grade trisodium citrate — not a monthly citric drum descale (that is Service-it).
- “Limescale prevention with every wash”
- “Removes dirt residue, odours and rust”
- “Helps your washing machine live longer”
Proprietary Blend & Dosage Breakdown
The labelled active is Polycarboxylates (with sodium citrate in older tabs) at 22%. Everything else in the pack is tablet binders, cellulose and perfume.
At 22% 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 99% Trisodium citrate dihydrate (food grade), mixed to 10 g per wash in the detergent drawer (hardness sequester).
- Labelled active
- Polycarboxylates (with sodium citrate in older tabs)
- 22%
- Carrier
- Tablet binders, cellulose and perfume
- Retail pack
- 390 grams (30 tablets) · £10.50
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Trisodium citrate dihydrate (food grade) at 99% bulk. Indexed as CAS 6132-04-3, formula Na3C6H5O7·2H2O. Buy it as 1 kg for around £9.49 from Amazon UK.
Working strength: 10 g per wash in the detergent drawer (hardness sequester). Indicative cost £0.09 per diluted litre — 70% 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.
- Gloves optional for a dry scoop. Do not mix with bleach or a toilet acid in one jug.
- Weigh 10 g of trisodium citrate dihydrate into the detergent drawer with your usual wash dose — a typical every-wash hardness sequester, not a 75 g/L Service-it drum clean.
- 1 kg at 10 g per wash is about 100 washes. A 30-tab Calgon box is thirty of those doses at grocery-tab prices.
- This is not identical to the current polycarboxylate polymer. It is the citrate hardness job from older Calgon SDS sheets. For a quarterly heater descale see the Service-it citric teardown.
- Store dry. Keep the sack labelled and away from children.
Dilution recipe
1 L working batch
Working strength 10 g per wash in the detergent drawer (hardness sequester). Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
10 grams
Trisodium citrate dihydrate (food grade)
Water
1 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 brandedCalgon | Raw active dupeDupeStack |
|---|---|---|
| Product | 4-in-1 Limescale Protection TabletsAmazon UK search — listing, not a confirmed seller | Trisodium citrate dihydrate (food grade) |
| Pack / unit | 390 grams (30 tablets) · £10.50 | 1 kg · £9.49 |
| Active | Polycarboxylates (with sodium citrate in older tabs) at 22%Carrier: Tablet binders, cellulose and perfume | 99% bulkNa3C6H5O7·2H2O |
| CAS number | Not disclosed on pack | 6132-04-3 |
| Working strength | Ready-to-use pack | Dilute 10 g per wash in the detergent drawer (hardness sequester) |
| Cost per litre | £10.50 / pack | £0.09 / L mixed from bulk |
| Headline saving | Baseline | 70% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene) |
Active ingredient and cheaper alternative — FAQ
Is Calgon the same as Dr. Beckmann Service-it?
Same aisle, different job. Service-it liquid is ~7.5% citric for an empty hot maintenance wash. Calgon is an every-wash sequesterant (polycarboxylate / citrate). See the Service-it teardown for the heater descale; use this one for the drawer dose.
Is sodium citrate the same as citric acid?
Related but not the same salt. Citric acid (CAS 5949-29-1) is the acid descaler. Trisodium citrate (CAS 6132-04-3) is the buffered hardness chelator used in food and in older Calgon tabs. Do not pour 7.5% citric into every wash expecting a Calgon tab.
How do you mix the 4-in-1 Limescale Protection Tablets dupe stack?
Gloves optional for a dry scoop. Do not mix with bleach or a toilet acid in one jug. Weigh 10 g of trisodium citrate dihydrate into the detergent drawer with your usual wash dose — a typical every-wash hardness sequester, not a 75 g/L Service-it drum clean. 1 kg at 10 g per wash is about 100 washes. A 30-tab Calgon box is thirty of those doses at grocery-tab prices. This is not identical to the current polycarboxylate polymer. It is the citrate hardness job from older Calgon SDS sheets. For a quarterly heater descale see the Service-it citric teardown. Store dry. Keep the sack labelled and away from children.
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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More teardowns
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- Retail pack
- £9.001 kg tub
- Raw active
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Domestos Original Thick Bleach
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- Retail pack
- £2.20750 millilitres
- Raw active
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Cillit Bang Limescale Destroyer
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- Retail pack
- £3.50750 millilitres
- Raw active
- Citric acid monohydrate (food grade)5949-29-1
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£16.50Save 70% / L
Indicative DIY stack