Posted: 18/02/2018 at 10:39
The thing is, that even home made remedies, if they are going to kill algae, lichens etc, will kill plants and mico-organisms too. Vinegar is a chemical - acetic acid. Salt is a chemical - sodium chloride, washing soda is sodium carbonate ... they're the sort of thing that people sometimes recommend as home remedies for all sorts of things but they're still chemicals and what is more they've not been properly tested as to efficacy or possible harm to the environment as garden solutions.
Elbow grease followed by sunshine and dry weather ... they're the best chemical-free cures for algae I'm afraid.