New to roof/patio cleaning (chemicals)

Hello, I'm just doing some research on chemicals on which would be best for which jobs. So far I've come across two types hydro and bac50 I was wondering what the difference would be in strengths or even use of each of these products is there also any other products people would recommend to either replace these two or for example an aftercare chemical that can be applied once everything has been removed from the roof or patio.