Ok I need an expert. Last night I brewed a 5 gallon batch, cooled it, and aerated for 40 mins. I woke up this morning and it was already pushing some crud out of the blowoff tube.... Which is too soon based on my experience (although I did used yeast that I harvested one week prior and pitched to a starter 2 nights before- don't know if that would cause it to started sooner than a fresh pack of yeast). Anyway, I was suspicious so I am thinking there wasn't much oxygen for yeast reproduction and build up.... So I took my diffusion stone - the whole aeration kit purchased from morebeer- tested it in water and there were only two streams of bubbles. I have another diffusion stone, so my question is if there's any positive or negative effects with trying to aerate right now, after signs of fermentation have started? Will it help the yeast, or has the damage been done?
Thanks a lot!