I find that Sydney's water is very low in Ca, SO, Cl. so it needs some addition IMO, especially calcium. I find 4 to 6 grams of salt is enough in most cases. Malty beers (e.g. Scottish ales, helles, viennas etc.) I use 4-5 grams of CaCl2. Pils and Dortmunders CaCl2 2-3 grams, CaSO 2-3 grams...