I've tried the gardening method. It doesn't work. Before you know it, you'll be pulling stuff out by double-handfuls and cussing at the runners which are all through the sand, rocks and wrapped around your corals. I've spent hours with tweezers and a scrub brush.
Pull it out and set up a refugium if you like green
It looks like progress. Now you have succesful plants and hermits. Just think about what comes next. Like I said mushrooms might be a good place to start. Someone else will have to advise you on which fish would be best. I am not sure.