My dock is made from cedar but it’s become very slippery, covered in some kind of mould. Is it safe to use oxygen bleach when I live near a lake?

Raymond, Vancouver

Oxygen bleach is made with hydrogen peroxide or a mix of hydrogen peroxide and washing soda. It’s gentler and less toxic than traditional chlorine bleach. Although it’s safer for the environment – without harsh fumes or the chance of creating dioxins – it’s best to dilute it and use it sparingly.

A thorough clean with a hose – a pressure washer will have too much force and splinter the wood -- concentrating on the cracks between the boards, will remove debris. Maintenance of your dock (or deck) is also important. Try this technique at least once a year. Even regular sweeping will keep the surface free of debris, keeping many types of stains or mildew at bay.

And don’t be overwhelmed by the store shelves full of wood cleaning products. Many contain toxic chemicals like oxalic acid, which is very corrosive. If manual removal of mould and mildew doesn’t work, choose oxygen bleach or a product with citric acid (from lemons and limes).

The fishes and I thank you for being an excellent steward of your lake habitat.

David Suzuki Foundation
Lindsay Coulter gives you the straight goods on living green. Send your questions to For more great tips, visit The David Suzuki Foundation at

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