Do you have green algae or mold on your patio?

Green algae (often referred to as “cyanobacteria”) can be a real nuisance. It not only looks bad, but it can also be dangerous if left untreated.

Don’t worry, in this article, I’ll show you the step-by-step process of how to remove green algae from your patio and backyard safely and effectively.

The best way to remove green algae is by spraying a algae removing solution on your patio and then using a pressure washer to rinse off the chemical you just sprayed on your patio.

First, let’s explain why green algae forms on patios in the first place.

Why Do I Have Green Algae On My Patio?

Green algae forms when light has been restricted from reaching the surface of your patio. This can be caused by overhanging trees, bushes, or even buildings.

As the rainwater settles on the surface of your patio, it creates the perfect environment for green algae to form.

When the algae forms it becomes slippery and can become a slip hazard. If you have young children or elderly people living in your home, this can be a real safety issue.

In some cases, green algae can also cause staining on your patio. This is because algae produces a substance called chlorophyll.

Chlorophyll is what gives plants their green color. When chlorophyll stains your patio, it can be very difficult to remove.

Moss also grows in shady, damp areas. If you have moss on your patio, it’s likely that you also have green algae.

You generally don’t notice it as much during the spring and summer months because the sunlight is more plentiful. But, as soon as the days start to get shorter and there’s less sunlight, the green algae growth increases.

So, now that you know why you have green algae on your patio, let’s move on to the next step: how to remove it!

How To Remove Green Algae From Your Patio

Before you start the process of removing green algae from your patio, it’s important to understand that there is no single “magic bullet” solution.

The best way to remove green algae from your patio will vary depending on the severity of the problem.

Also, the process I’m going to outline is effective on paving slabs, paving stones, paving tiles, flags, fences, pathways, driveways and decking.

Removing with chemicals

I’m not a big fan of chemicals and mostly believe in natural solutions. However, when it comes to green algae, sometimes you just need the extra power that chemicals provide.

There are many different patio cleaners available on the market. Some of them are specifically designed to remove green algae, while others are general-purpose cleaners that will do the job just as well on your patio.

If you decide to go this route, I would recommend using a product recommended and one that has decent reviews.

If you have to use a chemical, then I would recommend HG. There are others such as Patio Magic, Rob Parker’s Best Algae Remover, and Wet and Forget which will also do the job.

Tools needed:

  • Pressure washer
  • Stiff brush
  • chemical algaecide like HG
  • Garden sprayer

Step 1 – Brush the surface

Now, this first step is entirely optional. You only really need to do this if there is quite a buildup of debris on the surface of your patio.

Simply starting to pressure wash this area would result in a lot of splashing and potentially cause damage to nearby surfaces. So, it’s best to remove any loose debris before you start pressure washing.

You can do this by using a stiff brush to scrub the surface of your patio. This will loosen up any dirt, leaves, or other debris that might be stuck to the algae. Once you’ve brushed the surface, you can then start pressure washing.

Step 2 – Use a pressure washer

In the vast majority of algae-removing scenarios, a pressure washer will be your best friend.

By using a pressure washer, you can quickly and easily remove the vast majority of green algae from your patio.

If you don’t own a pressure washer, you can usually rent one from your local hardware store.

When using a pressure washer, it’s important to use the lowest setting possible. This will help to avoid damaging your patio.

Oftentimes people turn up the pressure too high and end up chipping or cracking their patio. So, start on the lowest setting and only turn up the pressure if necessary.

Related: How To Clean Your Concrete Patio (Without A Pressure)

Step 3 – Apply a chemical algaecide like HG

After you have pressure washed your patio, it’s a good idea to apply a chemical algaecide.

This will help to kill any remaining algae spores and prevent them from growing back.

There are many different brands of algaecide on the market. We recommend using HG’s Green Algae Killer. This product is highly effective and very easy to use.

Simply attach the garden sprayer to the bottle and then apply it to your patio. Be sure to follow the manufacturer’s instructions when applying the algaecide.

Step 4 – Repeat as necessary

In some cases, you may need to repeat steps 2 and 3 a few times before the algae is completely gone.

It can take up to 36 hours for the algaecide to take effect. So, if you don’t see any results after the first treatment, simply repeat the process.

Simple pressure washing (cleaning without chemicals)

In most cases, a pressure washer is your best friend when it comes to removing green algae from your patio.

Not only is it fast and easy, but it’s also very effective. In most cases, a pressure washer will be all you need to remove the green algae from your patio.

Tools needed:

  • Pressure washer
  • Stiff brush

Step 1 – Brush the surface

Just like the first example, it’s a good idea to brush the surface of your patio before you start pressure washing.

This will help to loosen up any dirt, leaves, or other debris that might be stuck to the algae. Once you’ve brushed the surface, you can then start pressure washing.

Step 2 – Use a pressure washer

If you don’t have a lot of algae, or if it’s not very thick, you may be able to get away with simply using a pressure washer.

Start by using the lowest setting possible. This will help to avoid damaging your patio. Then, move the pressure washer back and forth across the surface of your patio.

Be sure to overlap your strokes to ensure that you’re getting all of the algae.

Step 3 – Repeat as necessary

You may need to repeat step 2 a few times before the algae is completely gone.

How Can I Stop Green Algae From Growing On My Patio?

Stopping green algae from growing on your patio is a multi-step process. By following the steps outlined below, you can stop your patio from going green and significantly reduce the chances of algae growth in the future.

Improve drainage

One of the main reasons why green algae grows on patios is because of poor drainage. When water sits on the surface of your patio, it creates the perfect environment for algae to thrive.

To improve drainage, make sure that your patio slopes away from your house. This will help to ensure that water doesn’t pool on the surface of your patio.

You should also make sure that there are no gutters or downspouts draining onto your patio. If there are, redirect the water away from your patio.

Keep your patio clean

Another way to prevent green algae from growing on your patio is to keep it clean. Remove any leaves, dirt, or other debris that might be present.

You should also sweep your patio on a regular basis. This will help to remove any algae spores that might be present.

Apply a sealer

Applying a sealer to your patio is also a good way to prevent green algae from growing. The sealer will create a barrier that will make it difficult for algae to take hold.

Choose the right material

Don’t forget, If you are installing new fencing or slabbing, choosing materials that are impermeable and flat will help prevent a buildup better than porous, uneven surfaces.

Porous materials allow more air and moisture in, which encourages the growth of algae.

In general, hardwoods like oak, ash and walnut tend to be more porous whereas softer woods like pine, fir and cedar are less so.

Sandstone and limestone are examples of porous rocks; slate, marble and granite are examples of non-porous or impermeable rock.

There are many different types of sealers on the market. Be sure to choose one that is specifically designed for outdoor use.

Key Takeaways

  • If you’re looking to prevent green algae from growing on your patio in the future, be sure to improve drainage, keep your patio clean, and apply a sealer.
  • Choosing the right material for your patio can also help to prevent algae growth.
  • In most cases, a pressure washer will be all you need to remove green algae from your patio. However, if the algae is thick or stubborn, you may need to use a stiff brush in addition to the pressure washer.You may need to repeat the process a few times before the algae is completely gone.

By following the steps outlined above, you can stop your patio from going green and significantly reduce the chances of green algae growth in the future.

FAQs

Can you clean paving slabs with soda crystals?

Yes, you can clean paving slabs with soda crystals. To produce your own homemade chemical, just add a few tablespoons of soda crystals to a bucket of warm water and scrub the paving slabs with a stiff brush.

Can you use vinegar to clean algae from concrete?

Yes, you can use vinegar to clean algae from concrete. Just mix one part vinegar with three parts water and scrub the algae with a stiff brush.

Can you use bleach to clean algae from concrete?

Yes, you can use bleach to clean algae from concrete. Just mix one part bleach with three parts water and scrub the algae with a stiff brush.

Do I need to seal my patio after cleaning it?

It’s not necessary to seal your patio after cleaning it, but it’s a good idea to do so. This will help to prevent algae from growing in the future.

What is volvox?

Volvox is a type of green algae that is often found in ponds and other bodies of water. It is characterized by its round, sphere-like shape.

Can you spot remove algae from paving slabs?

Yes, you can spot remove algae from paving slabs. Just pour a small amount of vinegar or bleach onto the affected area and scrub it with a stiff brush.

In Summary

If you want to prevent green algae from growing on your patio, be sure to improve drainage, keep your patio clean, and apply a sealer. You may also want to consider choosing materials that are less porous and more impermeable.

In most cases, a pressure washer will suffice for removing green algae. However, if the algae is thick or stubborn, you may need to use a stiff brush in addition to the pressure washer.

You may need to repeat the process a few times before the algae is completely gone.

By following the steps outlined above, you can keep your patio looking its best.

About the Author

Passionate about helping households transition to sustainable energy with helpful information and resources.

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