Killing Algae Growing on a Wooden Deck Using Hydrogen Peroxide





Introduction: Killing Algae Growing on a Wooden Deck Using Hydrogen Peroxide

Hydrogen peroxide (H2O2) is great for cleaning (especially outdoors) because its fairly caustic at first, but changes into regular water after exposure to sunlight. It readily kills single celled organisms such as bacteria (or in this case algae) growing on almost any surface without damaging (for the most part) what's below it.

I used it to clean off the slippery when wet steps of a wooden deck.

This is going to be a short instructable.

Buy consumer grade H2O2 from the drugstore, get a good scrub brush, pour on, then scrub. I used 2 x 32oz bottles for this much. I could've made it go further if i had just scrubbed more however.

You want to let scrub it in for 30 seconds or so, and let it sit for a minute or 2. But then remove the foam (i just scraped it off with the brush) that will appear. That foam is mostly the dead bodies of whatever was growing there. Repeat a few times, then rinse off with a hose.

It will "smoke" and foam up a bit, this is normal. Don't worry about getting some on your skin, just rinse it off with water. You might want to keep a cup of it out there just in case. Take care not to get the H202 or the foam on the lawn, it will damage the grass.

I didn't really do a great job with "before" pictures, so the last few are a non-steps section of the deck that I wanted to show the difference. The last pic is the steps almost dry.



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    Drug store hydrogen peroxide is a 3% solution and considered topical, meaning you can apply it to skin. If you really want to step up your game for cleaning go to the beauty supply store where you can pick up 40% solution off the shelves. Get the liquid, not the cream and please read the safety instructions on the bottle. A 40% solution is considerably stronger and can affect the skin.

    Adding a bit of Mule Team Borax to the mix can also significantly improve the results. Oxacylic Acid found in Oxy Clean products also works. Another approach is to pre treat the area with a dilute mix of water and baking soda. Cover the area with the mix and let it dry. When you add the peroxide mix it will work much faster.

    Note that all of these preparations are what we regularly use to bleach wood. I would be cautious using peroxide around any dark or stained wood. It will be very difficult to keep the results consistent and you may seriously discolor the wood in areas.

    1 reply

    Hence why the 3% OTC stuff is usually sufficient

    This was fantastically helpful advice! We just realized that trick-or-treaters were likely to wipe out on the algae-ridden landing of our front steps. After reading your instructable I grabbed a scrub brush and a bottle of hydrogen peroxide, and five minutes later, our landing is safe for ghouls, witches and any other variety of Halloween visitor! Thank you!

    1 reply

    ? happy Halloween ?

    I have tried everything else now I will try this. Headed for the drugstore NOW!!

    try a product on amazon called neutra-sul it is 7% peroxide so a bit more powerful than drugstore grade. I paid about $7 for a gallon. I put the product in a spray bottle and sprayed all of my deck stairs on an overcast day and it completely eradicated the algae. I had to use a deck scrubber to break the algae free but teh parts that I could not scrub dried out and broke free from rain fall. now my 10 year old deck looks brand new and is no longer slippery. Thanks for the tip, I only tried because of this instructable!

    Consumer grade hydrogen peroxide is OK to "get on your skin"--it can be used to clean wounds and even as a mouthwash.

    I suggest mixing up a hydrogen peroxide and boric acid cleaning solution for killing algae/mold/mildew. Look for a much stronger hydrogen peroxide concentration than is available at the drugstore. Google is your friend here.

    Don't get it on your skin, wear gloves.