Consumer advocacy teardown
Clearwater pH Minus alternative & active ingredient dupe
Stop paying £9.99 for Clearwater. The bulk active is Sodium bisulphate (dry acid) — 56% less per working litre than a typical pack.
- Active
- Sodium bisulphate (dry acid)
- CAS
- 7681-38-1
- Dupe
- Sodium bisulphate (dry acid)
- Saving
- 56% / 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 1.5 kg pack of Clearwater pH Minus is about £9.99 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: Lowers spa and pool pH safely; Granular and easy to dose; and Protects against scale when pH is high.
The catch: 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.
- “Lowers spa and pool pH safely”
- “Granular and easy to dose”
- “Protects against scale when pH is high”
Proprietary Blend & Dosage Breakdown
The labelled active is Sodium bisulphate (dry acid) at 95%. Everything else in the pack is none.
Even when the pack is sold as “pure” or ready-to-use, the dose that actually does the work is Sodium bisulphate (dry acid). 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 95% Sodium bisulphate (dry acid), mixed to 0.5 g/L.
- Labelled active
- Sodium bisulphate (dry acid)
- 95%
- Carrier
- None
- Retail pack
- 1.5 kg · £9.99
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Sodium bisulphate (dry acid) at 95% bulk. Indexed as CAS 7681-38-1, formula NaHSO4. Buy it as 5 kg for about £14.50 from Amazon UK.
Working strength: 0.5 g/L. Indicative cost £0.00 per diluted litre — 56% 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 solid. Gloves, goggles, ventilation. Add acid to water, never water to acid.
- Test pH. A cautious spa starting dose is about 0.5 g per litre — then retest. Do not dump a whole tub.
- Predissolve in a plastic bucket of spa water and feed in front of a return jet.
- Wait 30 minutes with the pump running before adding more.
- Store dry, away from chlorine tablets (incompatible stack).
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
Sodium bisulphate (dry acid)
- Concentrate
- 500 g
- grams of solid
- Water
- 1,000 L
- carrier volume
- Batch cost
- £1.45
- 1,000 L working solution
- Saved vs retail
- £1.88
- 57% · retail £3.33
Estimated coverage at the listed rate: 0.8 m².
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedClearwater | Raw active dupeDupeStack |
|---|---|---|
| Product | Clearwater pH MinusAmazon UK search — listing, not a confirmed seller | Sodium bisulphate (dry acid) |
| Pack / unit | 1.5 kg · £9.99 | 5 kg · £14.50 |
| Active | Sodium bisulphate (dry acid) at 95%Carrier: None | 95% bulkNaHSO4 |
| CAS number | Not disclosed on pack | 7681-38-1 |
| Working strength | Ready-to-use pack | Dilute 0.5 g/L |
| Cost per litre | £9.99 / pack | £0.00 / L mixed from bulk |
| Headline saving | Baseline | 56% 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 extractionAcid-resistant PPE. Apron and gloves rated for corrosive liquids |
Active ingredient and cheaper alternative — FAQ
What is the active ingredient in Clearwater?
Clearwater pH Minus is labelled as Sodium bisulphate (dry acid) at 95%. The carrier is None. Pack size: 1.5 kg. The bulk equivalent we index is Sodium bisulphate (dry acid) (CAS 7681-38-1).
Is Sodium bisulphate (dry acid) safe on the intended surface?
Used at the listed working strength (0.5 g/L), 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 Clearwater pH Minus?
Yes. The bulk equivalent is Sodium bisulphate (dry acid) (CAS 7681-38-1). Indicative saving 56% per working litre versus a typical £9.99 pack. Working strength: 0.5 g/L. Live shop prices move.
How do you mix the Clearwater pH Minus dupe stack?
Corrosive solid. Gloves, goggles, ventilation. Add acid to water, never water to acid. Test pH. A cautious spa starting dose is about 0.5 g per litre — then retest. Do not dump a whole tub. Predissolve in a plastic bucket of spa water and feed in front of a return jet. Wait 30 minutes with the pump running before adding more. Store dry, away from chlorine tablets (incompatible stack).
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
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- Retail pack
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- Raw active
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- Retail pack
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- Raw active
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- Retail pack
- £11.991 kg tub
- Raw active
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DIY stack · 56% / L vs branded
£27.48indicative kit · Amazon cannot add a mixed search kit as one basket