The key difference is what they target. A moss killer (biocide) kills biological growth like moss, algae, and lichen using active ingredients such as benzalkonium chloride. A patio cleaner (surfactant) lifts non-biological dirt, grease, and grime from the surface. If your patio has turned green or black, you need a biocide. If it is simply dirty or grey, a surfactant cleaner will do the job. Many people buy patio cleaners expecting them to kill moss, but most standard cleaners do not contain biocide ingredients.
Need a Biocide That Actually Kills Moss?
GoodGrow Moss Killer is a benzalkonium chloride biocide. It kills moss, algae, and lichen on patios, driveways, and hard surfaces. Spray and leave. No pressure washing required.
The Confusion: “Patio Cleaner” Means Different Things
“Patio cleaner” is one of the most misleading search terms in outdoor maintenance. It sounds straightforward, but the phrase covers at least three completely different product categories, each designed for a different problem.
If you search for “best patio cleaner UK” right now, the results page will show you surfactant-based degreasers, biocide-based moss killers, acid-based stain removers, and even pressure washer detergents, all under the same umbrella term. No wonder people end up buying the wrong thing.
The cost of getting it wrong is not just money. It is time. You apply a product, wait days or weeks for results, and nothing changes because you were treating dirt with a biocide or treating moss with a degreaser. Neither works on the other’s problem.
This guide breaks down the three main types of product sold as “patio cleaners” in the UK, explains exactly how each one works, and helps you choose the right one for your situation in under five minutes.
Type 1: Biocide-Based Products (Moss Killers)
What they do
Biocides kill living organisms. On patios, that means moss, algae, lichen, and mould. They work by penetrating the cell walls of biological growth and destroying it from the inside. The visible result is that green, black, or orange growth on your patio dies, dries out, and either washes away naturally with rain or can be swept off.
Active ingredients
The most common active ingredient in UK biocide patio products is benzalkonium chloride, a quaternary ammonium compound. It is widely used in professional-grade treatments for hard surfaces because it is effective at low concentrations, has a residual protective effect, and does not damage most paving materials.
You will also see products containing didecyldimethylammonium chloride (DDAC), which works in a similar way. Some older formulations use sodium hypochlorite (bleach), though this is technically a disinfectant rather than a targeted biocide and has significant drawbacks including surface discolouration.
When you need a biocide
If your patio has turned green, has black patches of algae, shows orange or white lichen growth, or feels slippery underfoot when wet, you have a biological growth problem. No amount of scrubbing or degreasing will solve this permanently. You need something that kills the organisms and prevents them from returning.
Biocides are the right choice for moss on patios, algae on paved areas, lichen on natural stone, and mould on any outdoor hard surface. Most spray-and-leave biocides continue working for several months after application, which means they also help prevent regrowth.
What they do not do
Biocides do not remove non-biological staining. Mud, oil, tyre marks, rust, and general grime will not be shifted by a moss killer. If your patio is both green and dirty, you will need to treat the biological growth first, then clean the surface separately.
Type 2: Surfactant-Based Products (Surface Cleaners)
What they do
Surfactants reduce the surface tension of water, allowing it to penetrate and lift dirt, grease, oil, and grime from hard surfaces. Think of how washing up liquid works on a greasy plate. Surfactant-based patio cleaners work on the same principle, just with stronger formulations designed for outdoor use.
Active ingredients
These products contain various surfactant blends, sometimes combined with mild alkalis or solvents to boost cleaning power. Common ingredients include sodium lauryl sulphate, alcohol ethoxylates, and various proprietary surfactant blends. Some commercial degreasers also contain sodium hydroxide (caustic soda) for heavier oil and grease removal.
At the household level, warm water with standard washing up liquid and a stiff brush is a surprisingly effective surfactant cleaner for general patio dirt. It costs almost nothing and works well for routine maintenance.
When you need a surfactant cleaner
If your patio looks grey, dull, or dirty but does not have visible green, black, or orange biological growth, a surfactant cleaner is what you need. Common situations include mud splatter from flower beds, oil or grease stains from barbecues, general weathering and accumulated grime, and tyre marks on driveways.
Surfactant cleaners are also the right choice for routine maintenance cleaning after you have already dealt with biological growth using a biocide. Once moss and algae are dead and gone, periodic surfactant cleaning keeps the surface looking fresh.
What they do not do
Surfactant cleaners do not kill moss, algae, or lichen. They may temporarily remove some surface growth through the physical action of scrubbing, but because they have no biocide properties, the growth returns within weeks. This is the single biggest source of frustration for people who buy “patio cleaners” expecting them to deal with moss. The patio looks clean for a fortnight, then the green comes straight back.
Pressure washing falls into this category too. It physically removes growth from the surface but does not kill the organisms at root level, so regrowth is often faster than if you had done nothing at all.
Type 3: Acid-Based Products (Specialist Stain Removers)
What they do
Acid-based cleaners dissolve mineral deposits, cement residue, efflorescence (white salt deposits), and certain rust stains. They are specialist products designed for specific problems that neither biocides nor surfactants can solve.
Active ingredients
The most common is hydrochloric acid (also sold as muriatic acid or brick acid). Some products use phosphoric acid, which is milder and safer on certain surfaces. Citric acid-based products exist for very light mineral deposits but lack the power for serious stain removal.
When you need an acid-based cleaner
Acid cleaners are the right choice for a narrow set of problems: white efflorescence deposits on brick or concrete, cement splashes or mortar stains from building work, heavy limescale buildup, and certain types of rust staining. These are not everyday cleaning products. Most homeowners will rarely, if ever, need one.
What they do not do
Acid-based cleaners do not kill biological growth and should never be used as general patio cleaners. More importantly, they can cause serious damage to the wrong surfaces. Acid will etch and permanently discolour natural stone, including Indian sandstone. It can also damage coloured concrete, resin-bound surfaces, and any surface with a protective sealant. Always check surface compatibility before using acid-based products, and consider them a last resort for mineral staining only.
Comparison Table: Biocide vs Surfactant vs Acid
The table makes the critical point clear: only biocide-based products kill biological growth. If moss, algae, or lichen is your problem, check the label for benzalkonium chloride or a similar biocide active ingredient. If the label only mentions surfactants or cleaning agents, it will clean your patio but it will not kill what is growing on it.
Which Do You Actually Need?
Here is a simple diagnostic. Look at your patio right now and match what you see to the correct product type.
Your patio is green, black, or has visible growth: You need a biocide. This is moss, algae, or lichen, and only a biocide kills it at root level. A surfactant cleaner will wash off the top layer but it will come back within weeks.
Your patio is grey, dull, or has dirt and oil stains: You need a surfactant cleaner. Your patio is dirty rather than biologically colonised. Warm soapy water and a stiff brush may be all you need. For heavier staining, use a commercial patio degreaser.
Your patio has white mineral deposits or cement stains: You need an acid-based cleaner. This is a specialist job. Avoid acid on natural stone and always test on a hidden area first.
Your patio has all three problems: Treat in order. Biocide first to kill biological growth. Wait for the growth to die (usually 2 to 4 weeks). Then use a surfactant cleaner to remove general dirt. Only use acid if mineral stains remain after the first two steps. This order matters because scrubbing live growth off before killing it actually spreads spores and accelerates regrowth.
Most UK patios that have been neglected for a year or more need a biocide as the first step. The damp British climate is ideal for moss and algae, and biological growth is almost always present to some degree, even when the dominant visible problem appears to be general dirt. If in doubt, start with a biocide.
Where GoodGrow Fits In
We should be upfront about this. GoodGrow Moss Killer is a biocide. It is not a general-purpose patio cleaner and we do not pretend it is one.
Our product uses benzalkonium chloride as the active ingredient. It kills moss, algae, lichen, and mould on hard outdoor surfaces including concrete, block paving, Indian sandstone, tarmac, and resin. It is a spray-and-leave treatment, which means you apply it, walk away, and let it work over 2 to 4 weeks without scrubbing or pressure washing.
If your problem is biological growth (the green, black, or slippery kind), our product is designed for exactly that job. If your problem is non-biological dirt, grease, or mineral staining, you do not need our product. You need a surfactant cleaner or an acid-based stain remover, depending on the stain type.
We would rather you buy the right product for your problem, even if that means buying from someone else, than waste money on the wrong one. For a full breakdown of biocide-based options available in the UK, see our best moss killer UK buyer guide.
For a broader look at all the approaches to treating outdoor surfaces, our moss, mould, and algae hub covers everything from product choice to application technique.
Frequently Asked Questions
Do I need a patio cleaner or a moss killer?
If your patio has green, black, or orange growth on it, you need a moss killer (biocide). This kills biological organisms at root level and prevents regrowth. If your patio is simply grey, dusty, or has oil and dirt stains, a standard patio cleaner (surfactant) will clean the surface. If you have both problems, treat with a biocide first, then use a surfactant cleaner after the growth has been removed.
Are patio cleaners and moss killers the same thing?
No. They work in completely different ways. Patio cleaners are surfactants that lift dirt from surfaces. Moss killers are biocides that kill living organisms. Some products combine both functions, but most do one or the other. Check the label for active ingredients: benzalkonium chloride means it is a biocide, while sodium hypochlorite or surfactant blends indicate a cleaner.
Can I use washing up liquid to clean my patio?
Yes, for general dirt and grime. Warm water with washing up liquid and a stiff brush is effective at lifting surface dirt. However, it will not kill moss, algae, or lichen. Biological growth will return within weeks because washing up liquid has no biocide properties.
What is the best patio cleaner for Indian sandstone?
For Indian sandstone with moss or algae, use a benzalkonium chloride-based biocide. It kills growth without damaging the stone. Avoid acid-based cleaners on natural stone, as they can etch and permanently discolour the surface. For general dirt on sandstone, use warm soapy water and a soft brush rather than harsh chemicals.
Will a patio cleaner stop moss coming back?
Standard surfactant patio cleaners do not prevent regrowth because they do not contain biocide ingredients. They remove surface dirt but leave the conditions that favour moss unchanged. A dedicated moss killer leaves a protective residual barrier on the surface that prevents new growth from establishing for several months.
Can I use the same product on my patio and driveway?
In most cases, yes. Biocide-based moss killers work on concrete, block paving, natural stone, tarmac, and resin surfaces. Surfactant cleaners are also generally safe on all hard surfaces. The exception is acid-based cleaners, which should not be used on natural stone, coloured concrete, or surfaces with sealant. Always check the product label for surface compatibility.
Got a Green or Black Patio?
If biological growth is your problem, you need a biocide, not a general cleaner. GoodGrow Moss Killer is a benzalkonium chloride spray-and-leave treatment that kills moss, algae, and lichen on all hard outdoor surfaces.
