I did it again....(help with possible infection please)

Not sure what I have here. Backstory on the first time. Made an extract dortmunder. Stalled fermentation around 1.015 or thereabouts. Left it in fermentor for a while, checking on it occasionally. Decided it had stopped and pitched a pack of dry yeast. When I checked on it the next time, I had a layer of white scum on the top. Dry, powdery looking with bubbles trapped beneath the layer. Bottled anyway and even though I tried to pull beer from below the surface layer, the white film transfered to the bottles. Over a few weeks, it looked like it got absorbed into the beer. Started trying them and the first beer was a gusher. Got better the longer they sat, but always had a problem with too much head while pouring and even had a couple of bottle bombs.

But that beer is history. Now for my last brew...

Fermentation went really well and quick. 1.068 og and stopped around 1.015. Checked over the course of a couple of weeks and it didn't move. Beer looked good and tasted good every time. But I felt I could get some more out of it so I pitched some yeast that had been working on some wort for a couple of days. Let it go for a while and pulled the lid to check gravity. Uh oh....







This time looked worse. Saddened, I closed it back up and left it alone. Til tonight(9 days after pitching champagne yeast). Saw some airlock activity and it smelled like beer. Pulled the lid and most of the white scum had disappeared and I was greeted with what looked like normal co2 bubbles. Took a gravity reading and it was down to 1.012-1.011. Tasted it and it was much different than before. I don't want to say astringent, because I'm not sure how that tastes(have only read descriptions).

Now, I see people saying if it's infected, it will taste so bad you will want to puke. I didn't get that, but I still spit it out. Will I know FOR SURE if it's infected? Or is there some kind of middle road when it comes to that?

Leave it alone for a while and see what happens. A lot of great beers rely on 'bugs' from the air to flavor (sour) the beer.

There are no known pathogens that can survive in beer, so once you have alcohol in there, it's not going to kill you. The worst thing that can happen to it, is it turn to vinegar. For that it needs oxygen ....... so quit removing the lid every day and looking at it.

Leave it for 2 weeks and see what you have.

I've never added champagne yeast to any beer (never needed extra attenuation), so I am not speaking from experience, but from what I have read, champagne yeast probably will not help to bring down anything but the biggest of beers. It eats simple sugars and cannot concert the complex ones, and going from 1.068 to 1.015, you will have certainly used up all the simple sugars. That's 78% attenuation; depending on the yeast, you were most probably done .... quit messing with it and you might get a beer you can drink.

you could have a good bug infecting it, just let it ride for a while longer

1.015 should not be a stall with extract and that gravity. What yeast did you use? I bottled a few i thought was lacto. They are turning out great.I like 2 months botteling,every beer goes from good to great all the time.Every time.

The beer in question is not extract. That was the first batch. Well, I shouldn't have said stall for the bigger beer. But I wanted it drier so that's why I pitched the yeast at the end of the other one.

I wonder if lacto bacteria is present in the air around here. I don't know anything about wild yeasts.

I dont know how each wild yeast act but that looks like brett.Ive had a lacto which is a thin white paint like film that breaks and has bubbles. I have racked in the lacto infection and have not had problems with it.I would bottle it while tasting the sample to get an idea of it then segregate them and taste one every week to check for overcarbonation or whatever.
If you open an mess with your fermenter that could have done it. Leave it and bottle it after a month next time if the og is under 1.06.
If you leave it alone for 3-4 wks you shouldnt have problems with it,poking around in it inbetween may give you problems

It looks like Brettanomyces to me. Quit fiddling with it and come back in a few weeks. If it has bloomed by then, chunk it. If it has instead lessened, roll the dice.

Good luck.

I know everyone around here is hyped up on RDWHAHB mantra, but here are some facts:

Your beer looks infected, from everything you mentioned about these beers, they sound infected.

Its not going to get any less infected with time.

Its not going to "bounce back" and taste like what you wanted it to taste like with time.

Infections can cause off-flavors, undrinkability, gushers, inconsistent tastes.

Yes, bacteria are used to produce some styles of beer, but this wasn't one of those styles.

There is some flaw in your equipment and/or process that is leading to infections on a consistent basis (if you call 2 batches consistent, but I'd be worried). Unless you are happy with making sour/brett beers from here on out, you need to figure out what the problem is.

There are some excellent thread on here about how to deal with an infection...I'd start by throwing that bucket out.

Hope this helps, and I don't mean to mean to come off sounding like a Sh*thead. Its just that RDWHAHB isn't what you need to be doing right now if you want to make good, consistent homebrew. My 0.02.

Well, the lesson I learned is to stop checking on it. It seems I introduced the problem when I added the yeast. Either something in the air here(I do have a mold problem in places), or something else.

I made a good beer in the same bucket between these batches so I don't think that's the issue but ill sanitize hardcore after this batch.

Thanks all for the help. I'll report back when its over.

Bottled it today. The white scum had completely disappeared and it looked normal again.

I hope I don't have to toss this but time will tell I suppose.