Stonecare4U Patio Perfect also contains a biocide that helps to eliminate organic matter between slabs and grout, such as weeds, green growth, leaf mulch etc. Take care with your lawn and remember to wash off the cleaner thoroughly at the end of the cleaning process to minimise impact to your grass. Most marks, grime and dirt will disappear with only one application of Essential Patio Perfect, however, depending on the age and condition of your patio a second application may be necessary to give you the “good as new” look.