Everything we used to clean our limestone front steps from last year. Here’s how we cleaned them (I did not use a cleaner this year because we sealed it last year). This could apply to other stones but make sure to test out first. 1) pressure wash - the Ryobi one is a great value 2) spray and rinse with Zep concentrated pressure wash cleaner 3) use a soft scrub with dish soap mix with warm water - although it didn’t get out the algae + mildew, it helped a little before trying the bleach solution. some people skip this and go straight to bleach but i wanted to try out 4) for stubborn stains, mix 1 part bleach with 2 parts water and spray on. bleach is safe for limestone but test this in a small spot first to make sure it won’t damage your stone. leave for about 1 hour and rinse. 5) allow to completely dry before sealing with Rain Guard Sealer using a garden sprayer to protect from moisture, mold and mildew. fallcleaning LTKHome LTKSeasonal