Consumer advocacy teardown
Organic Lawn Moss Killer & Fertiliser alternative & active ingredient dupe
Stop paying £38.00 for Mo Bacter. The bulk active is Sulphate of potash (0-0-50) — 76% less per working litre than a typical pack.
- Active
- Potassium oxide (potash) with Bacillus subtilis
- CAS
- 7778-80-5
- Dupe
- Sulphate of potash (0-0-50)
- Saving
- 76% / 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 20 kg bag pack of Mo Bacter Organic Lawn Moss Killer & Fertiliser is about £38.00 in lawn & garden. 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: Destroys moss without leaving black dead debris; Naturally digests dead moss using beneficial bacteria; and Will not stain stone paving or decorative aggregate.
The catch: The moss dies because of high potash, not a magic organic patent. Sulphate of potash (0-0-50) supplies the same K2O without iron staining; a cheap Bacillus or compost-tea inoculant does the digestion step. A 20 kg 5-5-20 bag is mostly filler next to 10 kg of 50% K2O.
- “Destroys moss without leaving black dead debris”
- “Naturally digests dead moss using beneficial bacteria”
- “Will not stain stone paving or decorative aggregate”
Proprietary Blend & Dosage Breakdown
The labelled active is Potassium oxide (potash) with Bacillus subtilis at 20%. Everything else in the pack is organic compost and nitrogen/phosphorus base (5-5-20).
At 20% 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 50% Sulphate of potash (0-0-50), mixed to 20 g/m².
- Labelled active
- Potassium oxide (potash) with Bacillus subtilis
- 20%
- Carrier
- Organic compost and nitrogen/phosphorus base (5-5-20)
- Retail pack
- 20 kg bag · £38.00
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Sulphate of potash (0-0-50) at 50% bulk. Indexed as CAS 7778-80-5, formula K2SO4. Buy it as 10 kg for about £18.50 from Amazon UK.
Working strength: 20 g/m². Indicative cost £0.04 per diluted litre — 76% 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.
- Wear gloves. Apply 20 g per m² of soluble sulphate of potash — broadcast dry and water in, or dissolve at 20 g/L in a watering can.
- A 10 kg bag covers about 500 m². That is more potassium oxide than a 20 kg 5-5-20 lawn bag, without ferrous sulphate staining on stone.
- Water afterwards with an aerated compost tea or a broad-spectrum Bacillus lawn inoculant if you want the organic-matter digestion step.
- Keep off ponds. Store dry.
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
Sulphate of potash (0-0-50)
- Concentrate
- 200 g
- grams of solid
- Water
- 10 L
- carrier volume
- Batch cost
- £0.37
- 10 L working solution
- Saved vs retail
- £0.01
- 3% · retail £0.38
Estimated coverage at the listed rate: 10 m².
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedMo Bacter | Raw active dupeDupeStack |
|---|---|---|
| Product | Organic Lawn Moss Killer & FertiliserAmazon UK search — listing, not a confirmed seller | Sulphate of potash (0-0-50) |
| Pack / unit | 20 kg bag · £38.00 | 10 kg · £18.50 |
| Active | Potassium oxide (potash) with Bacillus subtilis at 20%Carrier: Organic compost and nitrogen/phosphorus base (5-5-20) | 50% bulkK2SO4 |
| CAS number | Not disclosed on pack | 7778-80-5 |
| Working strength | Ready-to-use pack | Dilute 20 g/m² |
| Cost per litre | £38.00 / pack | £0.04 / L mixed from bulk |
| Headline saving | Baseline | 76% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene) |
Active ingredient and cheaper alternative — FAQ
What is the active ingredient in Mo Bacter?
Mo Bacter Organic Lawn Moss Killer & Fertiliser is labelled as Potassium oxide (potash) with Bacillus subtilis at 20%. The carrier is Organic compost and nitrogen/phosphorus base (5-5-20). Pack size: 20 kg bag. The bulk equivalent we index is Sulphate of potash (0-0-50) (CAS 7778-80-5).
Is Sulphate of potash (0-0-50) safe on lawns?
Used at the listed working strength (20 g/m²), the dupe is the same chemistry as the branded pack for lawns, beds and pots. 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 Mo Bacter Organic Lawn Moss Killer & Fertiliser?
Yes. The bulk equivalent is Sulphate of potash (0-0-50) (CAS 7778-80-5). Indicative saving 76% per working litre versus a typical £38.00 pack. Working strength: 20 g/m². Live shop prices move.
How do you mix the Organic Lawn Moss Killer & Fertiliser dupe stack?
Wear gloves. Apply 20 g per m² of soluble sulphate of potash — broadcast dry and water in, or dissolve at 20 g/L in a watering can. A 10 kg bag covers about 500 m². That is more potassium oxide than a 20 kg 5-5-20 lawn bag, without ferrous sulphate staining on stone. Water afterwards with an aerated compost tea or a broad-spectrum Bacillus lawn inoculant if you want the organic-matter digestion step. Keep off ponds. Store dry.
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.
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DIY stack · 76% / L vs branded
£28.50indicative kit · Amazon cannot add a mixed search kit as one basket