Pool & spa
Clearwater pH Minus dupe
Why pay around £9.99 for Clearwater? The bulk active is Sodium bisulphate (dry acid) — 56% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Clearwater pH Minus
1.5 kg · £9.99 typical snapshot
None
2 · Active
Sodium bisulphate (dry acid)
95% on the label
7681-38-1NaHSO4
Bulk Sodium bisulphate (dry acid)
3 · Mix
0.5 g/L
£0.00 per working litre · 56% less than the shelf 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.
Label teardown
What the pack promises versus what the label chemistry actually is.
The marketing claim
“Lowers spa and pool pH safely”
The chemical reality
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.
Active vs filler
95% Sodium bisulphate (dry acid) · 5% carrier / filler — None
- Typical retail
- £9.99
- 1.5 kg
- Estimated active cost
- £4.35
- Scaled from bulk £14.50 / 5 kg
- Indicative markup
- 2.3×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 1.5 kg pack of Clearwater pH Minus typically retails around £9.99 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: 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 around £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).
Dilution recipe
1,000 L pool / spa volume
Working strength 0.5 g/L. Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
500 grams
Sodium bisulphate (dry acid)
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 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 pack that typically retails around £9.99. 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 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.
Related guides
Pool guide
Pool and spa basics: pH, chlorine and cyanuric acid without the brand kit
What Clearwater-style pH Plus, pH Minus, chlorine and CYA actually are — soda ash, dry acid, TCCA and stabiliser — with links to DupeStack teardowns.
Pool guide
Pool shock, bromine, floc and algaecide — not the same tub
Cal-hypo shock, dichlor granules, MPS oxidiser, BCDMH bromine, alum floc, copper algicide and thiosulphate reducer are different salts. Match the job before you buy a spa-shop tub.
Pool guide
Phosphate remover and polyquat — not a shock, and not copper
Lanthanum chloride drops phosphate. A polymeric quat is a copper-free algicide. Neither replaces trichlor, dichlor or cal-hypo, and neither is alum floc.
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 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.
Pool & spa
Total Alkalinity TA Plus
Clearwater
- Retail pack
- £11.991 kg tub
- Raw active
- Food / technical grade sodium bicarbonate144-55-8
Standard baking soda sold at a 1,200% retail markup under spa branding.
£27.48Save 56% / L
Indicative DIY stack