Originally Posted by SMOKEU
If my brew gets infected in the fermenter will there always be obvious signs of infection such as a growth on top or a nasty smell?
If a beer gets a true "infection" which is rare,
usually you will get a pellicule, which will look like a whitish skin on top, like this;
Or it will have things on the surface that hang down into the beer.
The beer may smell or taste a sour or it may smell/taste vinegary.
Not all infections are bad however, in fact many people brew Lambics and other sour beers and are proud of it.
Brettanomyces forms a pellicle- a lumpy white film yeast that coats the top of the beer in fermentation. The yeast cells form chains that can float on the top of beer making use of atmospheric oxygen, thus, Brett is an oxidizing yeast. The pellicle will form in the fermenting vessel (porous or non-porous) and help guard against oxidation during the long aging / fermentation time. The pellicle also guards against acetobacter.
The beer may actually be fine under it....or it may be slightly funky, and enjoyable, or you may have to dump it, if it smells or tastes too bad...but you wont know until you draw a sample and taste it.
(remember, nothing that can harm you, or make you sick can grow in beer, so don't worry about tasting it.)
Not knowing anything about your beer/recipe, and whether or not that is in your primary or secondary, or how long it's been there.
(Hint hint, the more info you give us, the better we can help you)
But most of the time what new brewers think is an infection, is just normal fermentation which is ugly, combined with newbish nerves...
Seriously one in every 150 "do I have an infection" thread is an actual infection.
And even then the beer might still be very drinkable....Maybe a little tart.
Because if you read the info in these threads, you'll see actually how difficult, especially with new equipment and even the most basic of sanitation practice...the beer will be fine.
SO more info, and pictures please, but I will say it over and over, it is really difficult for a new brewer in their first couple batches to get an infection. It is more likely that I will get one in the 10th or 30th or 50th batch as my gear gets banged up a bit....