The moss, grime and damage

Unattended parts of walkways exposed to rains in Kerala are potentially dangerous. A few friends faced the wrath of these walkways. Moss grew and made the walkway beautiful to look at, but dangerous to walk on. They fell - thankfully with no major damage. One friend said, I can bring a pressure pump and wash it away. But my question was - won’t it grow again? Another said, Use bleach. We did, but it gave only minimal, temporary benefit. The third semi-permanent solution was to cover the walkway and protect it from rain, which we tried, but damp groundwater still seeped in. The only permanent solution seems to be taking the stones out and replacing them with moss-resistant stones. But that comes with a cost. We were about to settle for the pressure pump solution - but there were three issues. Water under pressure can damage stones. Moss will grow again. And pressure pumps cost a bit too much! At times, my heart looks a little like those moss-filled pathways, waiti...