How to soft wash red algae if it turns pink, yellow or orange

February 02, 2022

How to soft wash red algae if it turns pink, red, yellow or orange

A customer told us he'd soft washed red algae on a rendered wall with Lightning Cleanze, and was worried because areas of the render had 
turned pink, yellow or orange. So he asked us what he should do about the red algae changing colour so dramatically.

Why does red algae change colour?

The change in colour of red algae is due to a brief and temporary flare up of the algae which happens naturally when it dies. Treated red algae will first turn pink and then go yellow or orange before disappearing completely. You will notice this more in hot weather.

Even some apparently clean-looking areas of render may flare up pink, yellow or orange immediately after treatment with Benz Lightning Cleanze or Bio Cleanze.

How to treat red algae if it turns pink, yellow or orange?

The fact is this is perfectly normal and nothing to worry about. Red algae will often dry to a light yellow or off-white before becoming dramatically cleaner over the next 24 hours.

For example, after treating red algae with Lightning Cleanze the flare up will usually disappear within 2-48 hours. And after treating with Bio Cleanze the flare up will usually be gone once dry and will return to a similar colour as before treatment.

The natural weathering effects of sun, rain and wind will then will gradually remove the remains of red algae over the following days, weeks and months. 

Take a look at this short video. It has a time lapse sequence at the end showing the long term effects of treating render with Benz Bio Cleanze. 

Quick tip: The most dramatic cleaning effect (the point whereby the customer is delighted with the results) will usually be noticed during a period of 7-14 days following treatment in warm weather and a couple of months in winter.

Why not just use stronger softwash chemicals?

Some contractors do not understand the biology of soft washing and so, thinking there is something wrong, use very strong chemicals in an attempt to stop red algae flaring-up and changing colour.

The result is they sometimes do stop flare-up but at the expense of damage to the substrate, their equipment, our environment, the health of the person doing the soft washing – and anyone else, such as customers and the general public, who happen to be in the vicinity.

Fortunately, when a contractor understands the biology of what is happening they can use much safer softwash chemicals, which benefits everyone and everything.

How to develop excellent customer relations

It's crucially important to clearly and accurately explain to your customer, in advance of treating the red algae, what results they can expect to see, why, and when.

It's a sound business principle of good customer relations that when your customer understands what is going to happen – before it happens – the possibility of their being concerned about the colour changes is eliminated. And simultaneously their trust and confidence in you, the contractor, skyrockets.

We hope this information is helpful and sincerely wish you great success in your soft washing business,

Ben, Leo, Fiona, Stevie & Anthony


Click here to explore all Benz softwash cleaning chemicals & equipment

Benz Softwash Bio Cleanze DDAC biocide & Benz Softwash Lightning Cleanze SH sodium hypochlorite biocide


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