I am trying to find the right power washer that will take dirt stains off large landscaping rocks. I live in northern CA and have many large rocks with red dirt stains from being underground that have been placed for landscaping and some that were used for rock walls. I don't know if I need a powerwasher that has an attachment for silica sand or something like that. I am not sure of what psi is right; I was looking at something around 3000 to 3500 psi, hoping it would do the job. I would like to pay no more than $1000 to $2000 for a quality powerwasher if there is one that could do this job. I might be thinking this device can do something it was not designed to do. If anyone could recommond a good powerwasher that might be able to do this job I would appreciate it. Maybe I need a sandblaster or something instead. Thanks for any help