The Bacteria often Mistaken for Mould

Updated: Nov 4, 2020

Gloeocapsa Magma

The black staining on this roof top is Gloeocapsa magma... Not mould!

Photo - Customer's home (Toobanna)

An ancient photosynthesizing cyanobacteria that converts water into oxygen gas,

Gloeocapsa magma is the chloroplast ancestor for all of Earth's plant life

Video - Customer's home (Alice River)

Gloeocapsa magma thrives in high humidity and low sunlight.

For the Toobanna home above, it grew only on this rear facing side of the roof.

Strange... I first thought...Until my research lead me to understand how perfectly natural it is for this bacteria.

First things first!

How does it grow?

Moisture and calcium carbonate or limestone, often found in roof shingles, nourish this single-cell organism, supporting colony growth and the gradual accumulation across an entire roof surface over time, where gravity influences its smear-like stain.

How does it spread?

Small groups of cells (spores) detach from colonies and relocate through wind and animals to continue their life cycle, doing this most successfully where there is low light.

Ah, ha!

The rear side of

the roof in Toobanna

must receive the

least amount of light...

Reduced light allows this bacteria to remain green, resembling algae,

but it is not!

Gloeocapsa magma is bacteria...

Photo - Customer's home (Kirwan)

What? Wait...

Why isn't the roof in Toobanna covered in green then?

To protect itself from high UV exposure, Gloeocapsa magma will develop a dark outer coating, such as seen in the roof at Toobanna.

This sticky secretion further increases this bacteria's durability, as it effectively affixes itself to a surface, remaining even after its death.

Once the bacteria

have become


the stains will

continue to worsen

year to year!

Symbiotic, or mutually beneficial, relationships between Gloeocapsa magma and fungi i.e. mould, often create completely different organisms named lichens. See below, how the edge of the concrete has been deteriorated by these organisms.

Video - Customer's home (Alice River)

Damage to Property

The literature reports agreement between the majority of field experts that Gloeocapsa magma is substantially damaging. As this bacteria holds moisture within roof shingles, left untreated, the materials age prematurely, corrode and lose particles, resulting in a roof's inability to reflect UV rays and shortening its life.


  • Increased air conditioning usage = Higher electricity bills

  • Chronic roof repair / reconstruction

  • Earlier roof replacement

  • Inferior property resale values

  • Insurance companies cancelling policies

Impact on Humans...

ALS (Amyotophic lateral sclerosis) is the subject of latest research connected with people experiencing exposure to significant levels of cyanobacteria toxins such as BMAA (B-Methylamino-l-alanine).

BMAA is a neurotoxin, affecting the brain and its ability to control muscles in all parts of the body. It can lead to Alzheimer's Disease and death, as the brain and body atrophy (waste away) due to the neurotoxin's degenerative effect on nerve cells.

It has been reported that ALS has had a 2.3 times increased chance of development for locals living within 800 m of lakes infested with cyanobacteria.

Options for eradication...


most common


widely accepted


is an

application of

Sodium Hypochlorite


Copper Sulfate

This works well for spot treatments.

However, not every family has the time for this :-)

What about larger, more difficult areas?

Video - Customer's home (Kirwan)

Video - Customer's home (Kirwan)

Like your gutters, eaves or roof?

Video - Customer's home (Kirwan)

Preferred technique

Non-pressure application of a properly proportioned detergent mix

Video - Customer's home (Charters Towers)

As this will avoid costly damage to... Property

Video - Customer's home (Kirwan)

Video - Customer's home (Kirwan)

Every home and it's situation is unique...

Our Kirwan home featured in this blog was living with a milder case of Gloeocapsa magma. Hence, Softwash North Queensland was able to effectively remove it on the day of this External House Wash. 2 applications of our SOFTWASH cleaning solution to the areas affected by Gloeocapsa magma were required. Being an External House Wash, the solution was also rinsed off, taking the dead bacteria with it.

For our home in Toobanna, the infestation was severe. Therefore, treatment in this case involved repeated application, as for our Kirwan home. However, the cleaning solution was not rinsed off, instead being left on to work through the sticky structure of the Gloeocapsa magma.

Pleased with the results

Our customer sent this photo of their roof a few days later...

Photo - Customer's home (Toobanna)

The cyanobacteria are dead!

They are no longer active...

No longer deteriorating this roof surface

The flaking seen above is the Gloeocapsa magma lifting off...