How to clean retaining rock wall?

[meghannstewart]

 

 

Hi Guys 

Our house has a rock retaining wall which is desperate for a clean. I tried with the pressure washer but it turns the rock white and strips the colour- you can see what I mean in one of the pictures. 
Hoping there is a trick that I just don’t know about. 
Thanks guys! 

[EricL]

Hello @meghannstewart 

Thanks for sharing your question about cleaning your rock wall. The stain that has imbedded itself on the stones is black mould fungus. Commonly found in household bathrooms, black mould tends to form in areas that are wet and warm. 

I recommend using 30 Seconds 5L Outdoor Cleaner Concentrate in combination with Oates S Shaped Synthetic Scrub Brush. I suggest using only your garden hose at low setting to wash the rocks to prevent bleaching the colour out of them. Please make sure to give the 30 second cleaner enough time to activate before washing it off.

Please make sure to wear personal protection such as gloves and goggles when using the cleaner.

If you need further assistance, please let us know.

Eric