Those dark streaks running down your tiles aren't just dirt — they're a living algae colony called Gloeocapsa magma. Pressure washing won't fix it. We kill it at the root so it stays gone.
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If you've noticed dark black or grey streaks running down your roof tiles, you're looking at Gloeocapsa magma — a cyanobacteria that's extremely common on roofs across Queensland's humid climate. It forms a dark protective outer layer as it grows, which is why it appears as those characteristic dark streaks rather than a typical green mould. The bad news: pressure washing scatters the spores and the colony re-establishes within 6 to 12 months. The good news: soft washing with the right chemical solution kills the organism at root level — stopping regrowth for 12 to 24 months. Burnett 2 Bay Soft Wash removes Gloeocapsa magma from roofs across Redlands, South Burnett, the Gold Coast, Ipswich, Logan and all of South East Queensland.
Gloeocapsa magma thrives in Queensland's subtropical humidity. It feeds on the calcium carbonate in concrete tiles and produces airborne spores that spread across your roof and to neighbouring properties. The dark colouring comes from a pigmented sheath the bacteria produces to protect itself from UV radiation — which is also why it's so resistant to simple washing.
High-pressure washing blasts the visible layer of growth off the surface but leaves the root system and spores intact. In fact, the force of pressure washing can scatter spores to previously unaffected areas of your roof, spreading the problem. Regrowth typically appears within 6 to 12 months — sometimes faster. It's a temporary fix that can make the underlying problem worse.
Soft washing applies a professional grade biocidal solution at low pressure. The solution penetrates the growth, kills the organism at the root, and then the dead matter is rinsed away. Because the bacteria has been killed rather than just displaced, regrowth is dramatically slower — typically 12 to 24 months before any significant re-establishment occurs.
Our soft wash treatment is safe on tile, colorbond, terracotta, concrete and metal roofs. No cracked tiles, no stripped coatings, no water forced under ridge capping. Before any work begins we assess your specific roof type and set the correct chemical concentration and pressure for it.
Black streaks on roof tiles are almost always caused by Gloeocapsa magma — a cyanobacteria that thrives in humid conditions. It feeds on the calcium carbonate in concrete tiles and produces a dark pigmented sheath that causes the characteristic streaking. It's airborne and spreads via spores.
With soft washing they will stay away for 12 to 24 months. With pressure washing alone, they typically return within 6 to 12 months because the root system and spores aren't killed — just displaced.
Yes. Soft washing uses low pressure and a chemical solution matched to your roof type. It won't crack tiles, strip coatings or damage ridge capping — unlike high-pressure washing.
Roof cleaning starts from $799 for a standard single-storey home, depending on roof size and growth level. Free quote before any work begins.
Serving Redlands and all of South East Queensland. We reply within 2 hours, Mon–Sat.
0412 291 614