So I just moved into a house that we're renting a few months ago, it appears the outdoor patio is limestone, and it's been raining a lot. The limestone now is completely black basically, its all stained and moldy I guess.

How in the world do we clean this?

 

http://www.findstone.com/curelime.htm

 

Have you had any personal experience? We dont have a power washer

 

Back before we bought a power washer, we used a scrub brush and warm soapy water. If it is really bad, you can use a splash of bleach.