Give the surface a decent scrub with a stiff bristle brush
Pour the cleaner onto the surface and give the area a really good scrub with a stiff bristle brush.
Leave it to do it's job for 15 minutes.
Get your back into it and give the area another good scrub. Hose down and wash off the suds. Leave to dry.
To maintain your patio, make sure you repeat this process every 6 months to prevent algae & mould re-growth.
Clean your equipment in warm water and detergent