How to Get Rid of Green Algae on Concrete

All concrete surfaces including patios, paths and driveways are susceptible to turning green. The cause of the green staining is most commonly due to the growth of microbiological contaminants such as algae, mould and lichen.

These organisms thrive in damp, shaded environments. They can quickly spread their spores which creates an unpleasant green film across concrete surfaces.

Why Does Concrete Go Green?

Concrete turns green due to the build up of biological growth, most commonly algae, mould and lichen. These microorganisms thrive in damp, shady conditions which makes gardens the ideal breeding ground. Animal deposits, fallen leaves and foliage feed the microorganisms causing them to spread on concrete surfaces.

This coupled with other external factors such as humidity, sunlight exposure and poor drainage contributes to the issue of biological growth.

Understanding the cause of the problem is the first step required to finding an appropriate solution.

Identifying Green Algae

Green algae is not the only cause of green on concrete. Other growth such as mould, mildew, lichen and moss can also contribute to green staining and growth. Different types of growth may require different cleaning methods.

Algae build up often appears as a green slimy film on top of the concrete. Mould, mildew and lichen usually look like dark spots on the surface. Moss, however, is much thicker and has a soft, plush, almost velvety texture.

Implementing Regular Maintenance

Biological growth can spread quickly, and catching it early means that less intensive methods are needed to achieve an effective clean. By ensuring you maintain your concrete surfaces regularly you can combat any issues before they get out of control.

Sweeping and rinsing your patio regularly will prevent biological matter from imbedding into the concrete. Carefully remove all debris from your concrete surfaces and remove standing water as these things offer microorganisms the nutrients and conditions they need to grow.

Inhibiting Algae Growth with Sunlight and Improved Drainage

There are some steps you can take to inhibit algae growth on concrete. Increasing sunlight exposure to your concrete surfaces will prevent growth as green algae thrives in damp, shady conditions.

Landscaping your garden by trimming back any overhanging branches, cutting back trees and thinning dense foliage will improve sunlight exposure. You can also consider the placement of garden furniture and plant pots as these contribute to damp and shade. Moving objects will prevent trapped moisture and allow the concrete to dry out.

Improving drainage in your garden will also be effective at preventing green growth. Installing appropriate drainage measures near your concrete surfaces will prevent standing water.

Standing water is a key contributor to the growth of algae. Other measures such as adjusting the slope of your land will also ensure water is directed away from your patio, path or driveway so that they can remain dry.

Applying an Algae Remover

Removing green algae from concrete is easy using a specialised commercial cleaner such as GK Path & Patio Cleaner. This professional grade, high-performance, long-lasting multi-purpose cleaner is designed to tackle 99.9% of organic and micro-biological soiling such as algae, lichen, mould and bacteria.

When using a commercial cleaner, it is important to follow the instructions for use to ensure optimal results. GK Path & Patio Cleaner will continue to break down biological growth over multiple months to offer longer lasting protection

Removing Algae from Concrete with a Pressure Washer

Pressure washing your concrete surfaces can also be effective at removing algae growth and reaching into the deeper pores of the concrete where algae can nestle.

When using a pressure washer it is extremely important to start on a low setting. If your pressure washer is too strong then this can damage the concrete. Start on a low setting and increase gradually should you need to.

Alternative Methods to Get Rid of Green Algae on Concrete

If you do not wish to use a commercial algae cleaning solution, then here are some alternative solutions. While these methods are effective at removing algae from concrete, they will not provide any long-lasting protection against regrowth.

Ensure that you are taking extra preventative measures to prevent algae from returning.

Removing Algae from Concrete with Vinegar

Create a solution by mixing equal parts white vinegar and water. Apply the mixture to the affected areas. Let this sit for 15-30 minutes (depending on the severity of the staining). Scrub and rinse thoroughly. The acid in white vinegar will kill the algae spores.

Removing Algae from Concrete with Bleach

Create a solution by mixing 1 part bleach with 3-4 parts water. Apply the mixture to the affected areas. Let this sit for 10-15 minutes. Scrub and rinse thoroughly. Remember to put protective measures into place to avoid contamination of ponds and plants as bleach is a harmful chemical.

Removing Algae from Concrete with Lemon Juice

For light staining, mix some lemon juice with water. Apply this to the affected areas. Let it sit for 20-30 minutes. Scrub and rinse thoroughly. The acid in lemon juice will kill the algae spores.

Removing Algae from Concrete with Salt

For light staining, dissolve some salt into water. Apply this to the affected areas. Let it sit for 20-30 minutes. Scrub and rinse thoroughly.

Applying a Sealer

Once you have cleaned your concrete and removed the algae successfully, you should consider applying a sealing solution to offer another level of protection for your concrete surfaces.

Using a sealer such as GK Invisible Stone Sealer will create a barrier that prevents algae from growing. This sealer will also offer protection against spillages to preserve the look of your patios, paths and driveways.

Summary

To effectively get rid of green algae on concrete, you can consider using a commercial cleaner or a household remedy. Make sure that you understand the limitations of certain methods to ensure you can prevent the algae from returning.

Other preventative measures can be taken to provide longer lasting protection such as using a sealer, increasing sunlight exposure to the concrete, and improving drainage. Algae thrives in damp, shady environments, so look for ways to combat this for future protection.