We worked hard covering pathways, steps and patio. Had dry weather so waited to see results. Nothing happened. No change to any part of the areas covered. My husband will go back to the slog of power washing.
Used to remove green from paving slabs, applied using an £8.99 Spear and Jackson hand pump sprayer as recommended on the bottle to allow the diluted Algon solution to be used sparingly and get best value for money.
Very effective in killing algal growth on the outside of our plastic polytunnel. Sprayed it on one sunny morning and within three or four days, all green had gone. Recommended and would buy again. Smells mildly of acetic acid, certainly not unpleasant to use.