I've never used either Happy Frog or Canna soil - when I grow in soil, I only use ProMixHP and no, you don't have to add anything to it - except nutes, that is - and the reason I like it is because I grow autoflowers and they don't like any nutes at all for the first couple of weeks - so I get to decide what and how much and when. Wouldn't grow anything in anything else...
Good luck!