Efflorescence coming through on Indian sandstone patio

Hi you will need a phosphoric acid solution do not use a regular based patio/driveway cleaner as they often contain hydrochloric acid. I have also heard that vinegar can be used but I'm not 100% on this. Hope this helps.

Hi. There are a few methods available to try. - jet washing. It’s fast and effective although has potential to remove any grouting in the joints. - scrub with a stiff brush and a warm water with vinegar and/or dish soap/baking soda solution. A 25%-50% ratio of vinegar in water. I haven’t tried this personally but should do the trick. - alternatively there are premixed solutions you can buy online but again I have no experience of using these and would try the others first.