  If the potion is a Splash Potion you add an additional 30 seconds and if it's a Lingering Potion you add an extra 60 seconds.<~><~>  To simmer the potion you must put 
the lid on the cauldron by right-clicking the cauldron with a /bwand/z or by using the interface. Once simmered the potion is complete and ready for the final phase.<~><~>  The 
final phase of brewing is the /bCompletion Phase/z. During this phase you can collect your potion with bottles or imbue it onto /bArrows/z and /bDiamonds/z if it is a lingering potion.