moss on a path

I am using Sulphate of iron, it kills moss but stains paving and tarmac. It is inorganic but the salts are soon neutralised and do no harm to surrounding soil. The staining will wash off and go lighter but many other caustic base cleaners will kill wildlife and plants.

There are some answers here: http://forums.moneysavingexpert.com/showthread.html?t=367264

i just get my jet wash out but ill try useing sulphate of ironhope they sell it at wilkos