Anyone working in soft-washing or facade cleaning has heard — or asked — this question: “If we tell our clients to stop using bleach, aren’t we simply moving them to another product they shouldn’t use either?” It’s a fair question, and the honest answer means looking past the single number most people reach for — pH — and examining the actual chemistry behind how each product cleans.

The “same pH, same risk” myth

Bleach (sodium hypochlorite) typically sits at a pH of around 11 to 13. Chemitek’s alkaline cleaning agents — including the products in the Drone Range — sit in a similar range. At first glance, that suggests similar risks. It doesn’t.

pH measures one thing: how acidic or alkaline a solution is. That’s genuinely useful for matching a cleaner to a contaminant — alkaline products work best on organic soiling (grease, soot, biological growth), acidic products on mineral scaling — and for flagging the extreme ends, where very strong acids or bases attack materials directly.

What pH cannot tell you is whether a product is safe for the surfaces, coatings, plants and soil around the cleaning zone. Two products can sit at exactly the same pH and have completely different safety profiles, because safety depends on several independent properties:

—  Oxidation potential (redox) — whether the product chemically attacks and destroys materials.

—  Ionic/salt residue — what’s left behind after the active chemistry is spent.

—  Selectivity of the mechanism — whether it acts only on the soiling, or on everything it touches.

—  Material-specific reactivity and ecotoxicity — the effect on metals, elastomers, plants and soil.

How bleach actually cleans

Household and industrial bleach is sodium hypochlorite (NaOCl). In water it forms hypochlorous acid (HOCl) and the hypochlorite ion (OCl⁻) — together known as free available chlorine, a powerful oxidising agent. That’s how it removes biological staining like algae, mould and lichen: through a redox reaction that oxidises and destroys the coloured pigments (so the stain visibly disappears) and oxidatively ruptures the cell structure of the organisms.

That’s exactly why bleach is fast and dramatic. But it’s worth being precise: bleach largely destroys the colour of a stain rather than removing the matter — the dead biomass often remains on the surface. And the property that makes it effective — strong, non-selective oxidation — is the very same property that makes it dangerous.

The three risks pH never shows you

1. Non-selective oxidation. Oxidation doesn’t distinguish between the pigment in algae and the pigment in anything else organic. The same reaction that erases a stain will bleach awnings, upholstery, painted render and dyed fabric, and will oxidise (burn) the leaf tissue of any plant it lands on. The chemistry has no way to tell a target stain from a garden bed next door.

2. Chloride-induced corrosion. Hypochlorite solutions are rich in chloride ions in an oxidising environment — the classic driver of pitting and crevice corrosion in aluminium and stainless steel, and attack on galvanised steel and anodised finishes. For solar work this is a direct hazard to aluminium panel frames, clamps and fixings. Oxidation also degrades the rubber and silicone in seals and gaskets over time — including the seals and junction-box gaskets on PV modules.

3. Sodium and chloride residue — the part that outlives the chlorine. This is the pathway most people miss. After the free chlorine has reacted or off-gassed, the sodium and chloride salts remain on the surface and in the runoff. Sodium degrades soil structure (it disperses clay and reduces water infiltration); sodium and chloride are both directly phytotoxic, causing leaf burn, osmotic stress and root damage. Runoff into beds and lawns means damage accumulates with every wash — which is why bleach can keep killing valuable planting around a property even though it “breaks down.” The same salt loading also acts on the building itself: it crystallises within the pores of porous render and masonry during wet–dry cycles, causing pitting, powdering, spalling and a progressive loss of surface strength.

None of these three pathways — oxidation, chloride corrosion, salt loading — is visible in a product’s pH value. Judging safety by pH alone leaves all three risks completely invisible.

How the Chemitek Drone Range works differently

The Chemitek Drone cleaners are surfactant-based. They lower the surface tension of water, then emulsify and lift organic soiling so it can be rinsed away. The soiling is removed, not oxidised in place. The formulations contain no oxidisers and no caustic components, so none of the three damage pathways above is ever triggered: no oxidative bleaching of pigments, no chloride to drive corrosion, and no sodium-salt loading of the soil.

For the exact job bleach is usually reached for — green and black biological staining — the Drone Stain Breaker is pH-neutral and bleach-free. It works by loosening the biological matter so that natural weathering and biological die-back clear it over the following weeks, rather than by oxidising it on the spot. Where an immediate visible result is needed, the alkaline Drone Surface Cleaning Agent - Organic at its heavy dilution does the job by lifting the growth — again without any oxidiser.

This is also why the Drone Solar Cleaning Agent is certified by ÉMI-TÜV Süd as safe for photovoltaic modules — including the aluminium frame, the anti-reflective coating and the silicone seals — with letters of conformity from major PV manufacturers. That certification is meaningful precisely because the product has no mechanism by which it could corrode the frame or attack the coating.

The “biodegradable” trap

Users are right to be sceptical of the word biodegradable. It describes what happens to a molecule after use — whether it breaks down in the environment — and says nothing about how toxic it is to a plant while it’s present, or whether it’s safe on a given surface. Products designed to kill plants can be biodegradable. For the same reason, no single label — biodegradability, EPA Safer Choice, “Certified for Outdoor Use” — fully guarantees safety for every surface and every species of plant. There is no certification that does.

So the defensible claim isn’t “100% safe.” It’s this: the Chemitek Drone Range is mechanistically in a different and far safer class than bleach, because it has no oxidative or salt-loading damage pathway — when the products are used at the recommended dilutions and with correct application discipline.

In the interest of honesty: one product needs client education. The Stain Breaker can affect sensitive plants if it’s misused — for example, applied undiluted. Used at the recommended dilution and method it remains in a completely different risk class to bleach, but it should never be sold as “spray-anywhere.”

Practical guidance near plants, paint and panels

—  Use the recommended working dilution for the product and the contamination. Stronger is not safer.

—  Where valuable planting is adjacent, pre-wet or shield it and rinse it down afterwards, as you would on any wash.

—  Rinse properly: correctly rinsed, the alkaline cleaners leave no residue — unlike bleach, which leaves salts behind by design.

—  For the Stain Breaker, dilute correctly and brief the client that it’s a slow, leave-on product.

—  Exact spray frequency depends on the substrate and soiling and is best set per project. The alkaline agents tolerate recurring use; bleach does the opposite — every repeat application compounds corrosion and salt loading.

The difference between bleach and the Chemitek Drone Range isn’t in the pH — it’s in the chemistry pH never showed. And it’s that chemistry, not a number, that determines whether a product is safe to use near solar panels, planting and facades.