[SukkoPera]

A proposito della questione "serve o no lo starter?" riporto, sempre dalle FAQ del produttore:

6. Do I need to make a starter for an Activator?

No.  The Activator is designed to deliver professional pitch rates (6 million cells/ ml.) when directly added to 5 gallons of wort. ( <1.060 at 70 degrees).  However, if a package is slow to swell, suspected of being mishandled, or if the date is approaching the six month shelf life it is a good idea to build the culture up with a starter.  High gravity or low temperature fermentations require higher pitch rates.  This can be achieved with inoculating with additional packages or making a starter.    

Quindi fino a 19 l a 21 ºC con max 1060 di densità, non serve. Sempre che il lievito sia fresco, ovviamente.