If you are looking for a way to remove green mold or algae from wood decking, there are a few things you can do.

In this article, we explain what green algae is, how it gets on your deck, and the best ways to remove it.

Let’s take a look…

What Is Green Algae?

If you have ever seen green slime growing on the side of a building or on rocks in a stream, you have seen algae. Algae is plant life that does not have flowers or seeds, and it can be found in both fresh water and salt water.

While most algae are harmless, some types can release toxins that can be harmful to humans and animals.

Green algae can be found growing on the surface of wood decks. It is often mistaken for mold or mildew, but algae will not cause the same type of damage to your deck that these other organisms can.

Algae is usually green, but it can also be yellow, blue-green, or brown. You might see it as a slimy film on the surface of your deck, or you might see it as a powdery substance.

Algae is not harmful to humans, but it can be unsightly. If you have green algae on your wood deck, you will want to remove it as soon as possible.

Related: How To Get Rid Of Black Spots On Patio Slabs (FAST!)

Why You Should Remove Green Algae From Your Deck

It is important to remove green algae from your deck for two reasons.

First, algae can cause your deck to become slippery. If someone slips and falls on your deck, you could be held liable for their injuries.

Second, green algae can damage the finish on your wood deck. over time, the algae will eat away at the finish, causing it to become dull and discolored.

If you do not remove the algae, it will eventually cause your deck to rot.

Related: How Does Pressure-Treated Wood And Lumber Work?

What Does Algae Like?

  • Debris
  • Shade
  • Moisture

Debris

The reason why green algae is often found growing on wood decks is that it likes to feed on the cellulose in wood.

If you have a lot of debris on your deck, such as leaves or twigs, this can provide food for the algae and cause it to grow.

Be sure to keep your deck clean and free of debris to prevent algae growth.

Related: Will My Patio Cleaner Kill Plants? (This Answer May Surprise You)

Shade

Green algae also likes to grow in shady areas. If your deck is in a shaded area, this can provide the perfect conditions for algae to thrive.

To prevent algae from growing, be sure to keep your deck in a sunny spot.

If you have trees or shrubs that are shading your deck, you may need to trim them back to allow more sunlight to reach the surface.

Related: How Do I Remove Green Algae From My Patio? (STEP BY STEP)

Moisture

Green algae also needs moisture to grow. If your deck is in a damp or humid environment, this can provide the perfect conditions for algae to thrive.

To prevent algae from growing, be sure to keep your deck as dry as possible.

If you live in an area with high humidity, you may need to take extra measures to ensure that your deck is not providing the algae with the moisture it needs to grow.

Removing Green Algae Stains From Wood

The best way to remove green mold and algae from wood or decking is to use white distilled vinegar or Ronseal decking cleaner with a stiff brush.

If the growth is heavy, you may need to use more than one application of the cleaner to remove all of the algae.

Once the algae has been removed, be sure to rinse the area with clean water to remove any residue from the cleaner.

White distilled vinegar is a natural disinfectant and will also help to kill any mold or mildew that might be present.

Ronseal decking cleaner is a commercial product that is specifically designed to remove mold and algae from wood decks.

Step 1 – Sweep the deck to remove any debris

Use a stiff brush to sweep the surface of the deck. This will help to remove any loose debris that might be present.

Step 2 – Mix one part white distilled vinegar with three parts water in a bucket

This is a fairly mild solution and should not damage the finish on your deck.

Step 3 – Apply the mixture to the algae-stained areas of the deck with a brush

This will be most effective if you can apply the mixture directly to the algae.

If the area is large, you may need to use a garden hose to wet down the area first.

Step 4 – Allow the mixture to sit for 10-15 minutes

This will allow the vinegar to penetrate the algae and begin to break it down.

Step 5 – Scrub the area with a stiff brush

Use a stiff brush to scrub the area where the green algae was present.

You may need to use some elbow grease to get rid of all of the algae.

Step 6 – Rinse the area with clean water

This is a really important step! Be sure to rinse the area thoroughly with clean water to remove any residue from the vinegar or the cleaner.

If you do not rinse the area, this can leave a film that will attract dirt and debris.

Step 7 – Allow the area to dry completely

Once you have rinsed the area, be sure to allow it to dry completely before walking on it or applying a new finish.

If you have a lot of green algae on your deck, you may need to repeat this process several times to remove it all.

You should also plan to clean your deck on a regular basis to prevent the algae from coming back.

Congratulations! You have now learned how to remove green algae from a wood deck. Be sure to follow these steps regularly to keep your deck looking its best.

How To Stop Algae Growing On Your Decking

To stop algae growth on your decking I recommend applying an inhibitor such as Ronseal Decking Protector.

This will help to keep the algae from coming back and will also protect your deck from weathering.

Be sure to follow the manufacturer’s instructions for best results.

FAQs

Does vinegar kill algae on decks?

Yes, vinegar is a natural disinfectant and will help to kill any mold or mildew that might be present.

Can I pressure wash algae off my deck?

Yes, you can pressure wash algae off of your deck. However, be sure to use a low pressure setting so that you do not damage the wood. Once you have done this you will need to apply an inhibitor to prevent the algae from coming back.

Related: How To Clean Patio Slabs (Without A Pressure Washer)

Can I use bleach to remove algae from my deck?

Yes, you can use bleach to remove algae from your deck. However, you should be aware that this will also kill any plants or grass that it comes into contact with. In addition, the bleach may damage the finish on your deck.

Can you paint over algae on decking?

Even though you can paint over the signs of algae on your decking, unfortunately, it won’t kill the live spores that are present. This means that the algae will continue to grow and will eventually come back through the paint. The best way to deal with algae is to remove it completely and then apply an inhibitor.

What is the best way to prevent algae growth on my deck?

The easiest approach to avoid algae on your deck is to clean it frequently and use an anti-algae product. You should also make sure there are no holes or flaws in the surface.

Is black mold/algae the same as green algae?

No, black mold and green algae are not the same thing. Black mold is a type of fungi that can cause respiratory problems in humans. Green algae, on the other hand, is a type of plant that often grows in damp or shady areas.

What are some common myths about green algae?

One of the most common myths about green algae is that it is caused by dog or cat urine. However, this is not the case. Green algae is actually caused by a variety of things including damp weather, shading, and excessive moisture.

How can I tell the difference between black mold and green algae?

Black mold is usually dark brown or black in color and has a fuzzy or velvety appearance. Green algae, on the other hand, is usually green in color and has a slimy or slippery texture.

About the Author

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

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