Don't think of your airlock as any accurate fermentation gauge....whether it bubbles or not, or stops is really not an indication of what is happening under the hood. Fermentation isn't always dynamic.
Your hydrometer is not your LAST resort in you mind after the thought of pitching more yeas...
It is the first thing you grab, if you are worried about your beer...even before posting an "is my beer ruined thread, or asking if something is wrong on here.
It often can take up to 3 days for the yeast to start fermenting your beer....they first have an orgy and grow an army, so it is perfectly normal for it not to start right away..and your beer will be safe while the yeast are getting down.
Your beer is not weak like a mewling baby...it has been brewed for over 4,000 years, EVEN before Louis Pasteur taught us about germ theory.
"Rules of Thumb" like the 1-2-3 rule AND USUALLY the instructions on your kit are really not the best info to go by. They are loose guides. In Mr Wizard's colum in BYO this month he made an interesting analogy about brewing and baking....He said that egg timers are all well and good in the baking process but they only provide a "rule of thumb" as to when something is ready; .recipes, oven types, heck even atmospheric conditions, STILL have more bearing on when a cake is ready than the time it says it will be done in the cook book. You STILL have to stick a toothpick in the center and pull it out to see if truly the cake is ready, otherwise you may end up with a raw cake.
Not too different from our beers. We can have a rough idea when our beer is ready (or use something silly like the 1-2-3 rule (which doesn't factor in things like yeast lag time or even ambient temp during fermentation) and do things to our beer willy nilly but unless we actually stick "our toothpick" (the hydrometer) in and let it tell us when the yeasties are finished, we too can "f" our beer up.
We forget this simple fact...We are not making koolaid, or chocolate quick, just stirring in and having instant gratification...when you pitch yeast, you are dealing with living micro-organisms...and they have their own timetable, and their own agenda...You have to figure in a wild card.
Any rule of thumb we talk about is usually based on observation. BUT like I said, it should be taken with a grain of saltbecause there are so many variables that come into play Not just things like the gravity of the beer (which the higher the gravity the longer things take) but things on a a level beyond our perception.
Just like with other animals, including humans...No two behave the same.
And finally, Remember this is a hobby, not brain surgery. It's meant to be fun not something we worry about.
I have found, really that the yeast are really pros at this brewing stuff.
And if after being asleep for 45 million years,
Old yeast, New Beer, they STILL can manage to wake up and brew a batch of beer. Then unless we are dumping them in boiling wort...
99% of the time they are working away happily whether we think they are or not.
It is very very very hard to ruin your beer it surprises us and manages to survive despite what we do to it.
I want you to read these threads and see.
https://www.homebrewtalk.com/f39/wh...where-your-beer-still-turned-out-great-96780/
https://www.homebrewtalk.com/f39/has-anyone-ever-messed-up-batch-96644/
And this thread to show you how often even a beer we think is ruined, ends up being the best beer you ever made, if you have patience.
https://www.homebrewtalk.com/f39/ne...virtue-time-heals-all-things-even-beer-73254/
Just remember to RDWHAHB, make that your mantra and you will be a successful homebrewer.
Oh this thread is really good too if you adopt the mindset in here you will do well...
https://www.homebrewtalk.com/f39/youre-no-longer-n00b-when-24540/
OH...and don't open your first beer til it has been stored for 3 weeks at 70 degrees or above....and don't panic if they aren't carbed yet, or don't taste quite right yet....they are green.