How to softwash red algae stains on render

May 30, 2018

Benz Softwash supply softwash chemicals to the professional softwash cleaning trade

We've been asked about the best way to softwash red algae stains from wall render.

After softwashing, light red algae will go from wall render in a few days in warm weather and up to two weeks in winter.

Heavy dark red algae on render can be problematic as it often has multiple layers of black algae underneath. So be prepared to give multiple softwash treatments.

Benz Bio Cleanze – when used as a stand-alone softwash treatment at up to 25:1 dilution – will clean red algae from wall render in a few months. A second application after a month or so is often advisable to remove any remaining red algae stains.

The fastest results come from softwashing the worst of the red algae with Benz Lightning Cleanze at 5:1 dilution (go to 4:1 if test results indicate this to be necessary but take care and use full ppe as it is getting quite strong at that dilution).

Then follow up with a treatment of Bio Cleanze, after thoroughly rinsing Lightning Cleanze from the wall render, at 40:1 dilution. Biocidal Wash will continue cleaning the red algae through time and impart residual protection against recolonisation.

Click here to learn more about softwashing wall render on our dedicated render page

Click here to read a more in-depth article on softwashing red algae from wall render

We hope this information is helpful.


Ben, Leo & Fiona

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

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