How do I know my beer is fermenting?
When the beer starts to ferment a thick foam will normally form on the top. This is quite normal and will protect the beer during fermentation. This should form within 24 hrs of the yeast being added. If nothing has happened within this time you may need to check the temperature of the room as it may be too cold. If the temperture is okay, leave for a bit more time. If nothing has happened after 48 hours then you may need to add yeast nutrient but have patience before taking this step.
The foam should die down after a couple of days, after which you should take a hydrometer reading. Bottle or barrel when the hydrometer readings have remained stable for a couple of days.