Originally Posted by Cpsurfer
I brewed my second ever AG batch on Sunday night, an IPA (OG 1.068) and everything went great right up until it was time to pitch the yeast.
Earlier in the day I had activated the Wyeast slap pack but after about 6 hours it had only swelled a little bit. I'd used Wyeast packs for my 3 previous batches with fantastic results and each time they swelled up huge in a matter of hours, this time not so much. Being a complete newb I didn't bother to make a starter but just threw it in the fermenter with the wort anyway.
Tonight it will have been 48 hours since I pitched and there has been no sign of airlock bubbles. I will give it one more day and then take a gravity reading, but my question is this: What should I do if after 72 hours there are no visible signs of fermentation?
1)Should I just re-pitch with new yeast?
2) Can I/should I re-boil the unfermented wort to kill off any nasties that may have taken root in the absence of viable yeast? Would this even make a difference or if infection has already begun is it too late to reverse the off flavors?
First of all, don't reboil! If you were sanitary, then the wort will be fine for a long time. If you reboil, all of your late hops additions become bittering hops, increasing the bitterness and losing the hops flavor and aroma.
Next, wait the full 72 hours, since you didn't make a starter. After 72 hours, check the SG. If it's exactly the same, you can repitch some yeast. I'd recommend a dry yeast like Nottingham, since you don't have a starter made.
I think you'll see some fermentation, though, so try to just wait it out! It should be absolutely fine.