Patios and driveways can fall victim to various types of stains, including moss, rust, oil, black and white lichen and more. 

Black spots, typically caused by algae, moss, or mould, can make patios appear dirty and neglected and are notoriously hard to remove.

Black spots cause problems by getting into pores, and they are a bigger problem on stones that have larger pores as part of their structure.

Owner of TGA Concrete Pumping, Tom Allen, has explained how to remove black spots from your patio with citric acid - a fairly common household item that is cheap to buy.

Tom said: “While household solutions like baking soda and vinegar are often recommended for cleaning, citric acid is another item readily available in supermarkets that can effectively tackle these stubborn stains.”

Aside from citric acid, you will need a large bucket, warm water, a scrubbing brush or broom with stiff bristles, and a watering can or spray bottle.

In the large bucket, mix approximately one cup of citric acid powder with one gallon of warm water. 

Stir the mixture until the citric acid has completely dissolved and adjust the quantities as needed depending on the size of the affected area.

Using a watering can or spray bottle, evenly apply the citric acid solution to the areas of your patio affected by black spots. Be generous with the solution, ensuring that it thoroughly saturates the surface.

Tom advised: “Allow the citric acid solution to sit on the affected areas for about 15 to 20 minutes. 

“This time gives the citric acid a chance to break down and loosen the black spots, making them easier to remove.”

After, use a scrub brush or broom with stiff bristles to scrub the patio surface vigorously. Focus on the areas where the black spots are most concentrated, applying extra pressure as needed to lift stubborn stains.

Once you’ve scrubbed the entire patio surface, thoroughly rinse away the citric acid solution using a garden hose or pressure washer. Ensure that all traces of the solution are completely removed.

This citric acid solution should be used at least twice a year to “prevent black spots from returning forever”.