I went down the path at the side of my cottage recently and nearly measured my length on the slippery paving stones. Time for action before someone gets hurt!
What is the solution?
There are two main ways of tackling slimy, algae-covered paths, patios and decking. You can use a pressure washer such as a Karcher – I tried this but found that the jet was so strong that the aging cement pointing was washed out. There is a circular attachment for patios which I found stopped excess spray but still did damage to the cement.
The second method is a chemical solution to kill the algae. Yes, but what about kids/pets/fish/ plants? I use Algon Organic Path and Patio cleaner. This product claims not use parabens, bleach or acid so is pretty safe – I qualify that because grass and other plant foliage will be scorched if it is touched but it does not seem to kill plants and the leaves will grow back. You are instructed to dilute the liquid with water and spray on. But I just put it in a watering can with a fine rose and water it onto my stone work; chosing a day when rain is not forecasted. You don’t need to scrub or rinse, just let it dry. It takes a few days for the algae to disappear but is quite effective. Make sure you rinse out your watering can after use.
Although Algon is pet-friendly, I keep our cats indoors until I am sure it has dried. Its effect is reputed to last for up to a year but as my path is in deep shade – and on a fairly steep slope – I tend to use it two or three times a year.