Age old newbie question: is it infected, or just ale yeast doing its thing?

[orgenomescii]

I pitched this batch of oatmeal Stout 13 days ago using US05. I just threw in the dry yeast without rehydrating it so I suspect that these floaty white things are dead or dormant yeast particles floating atop the wort but I'm not too sure. It fermented at about 20-25C for a few days and the yeast seemed to activate instantly once I pitched it. There was pretty vigorous fermentation activity during this time

But then the temperature dropped and it's probably been fermenting on the lower end of its limit, around 12-14C for the last week. Nothing smells off about it and from the last hydrometer measurement I took, it looks like it will hit my FG very soon.

So is this white stuff just dormant/dead yeast? If so how do I get it out of suspension? You can't really see in the pics but the wort is gently bubbling away.

 

[RM-MN]

Looks normal to me. Yeast rafts with possibly a bit of hops.

 

[IslandLizard]

So is this white stuff just dormant/dead yeast?

They're just tiny clumps of (live) yeast. Dead yeast cells don't clump like that, they tend to sink.

If so how do I get it out of suspension?

The little rafts will likely sink at some point when fermentation has completed.
Even if a few remain floating when you're ready to package (bottle, keg), they'll cause no harm. They'll eventually sink in the bottle or keg, ending up on the bottom.

On a side note, try to control your fermentation temps better, keeping it steady. A sudden temp drop can cause yeast (and fermentation) to stall, leaving you with under-attenuated beer that can be impossible or very difficult to resurrect.

 

[orgenomescii]

On a side note, try to control your fermentation temps better, keeping it steady. A sudden temp drop can cause yeast (and fermentation) to stall, leaving you with under-attenuated beer that can be impossible or very difficult to resurrect.

I had planned to keep a little space heater by it in the garage but didn't have the foresight to check if there was an outlet nearby (new home) and there wasn't. Lesson learned. Thankfully my wife took pity on the poor brew and agreed to let me leave it on the kitchen counter where at least the temp is consistent.

 

[IslandLizard]

Thankfully my wife took pity on the poor brew and agreed to let me leave it on the kitchen counter where at least the temp is consistent.

Our dear wifes, putting up with our fermentation projects!
Your beer will thank her in kind!

The fermenter doesn't have to sit on the counter, it could be tucked away in a corner, closet, pantry, anywhere temps don't fluctuate too much.
If on a tile/cold floor, put a thick blanket or towel underneath, or something else insulating.

Wrapping the whole fermenter with something insulating also helps to reduce temp fluctuations.

 

[AmarikinBrew]

Yep, normal yeast fleas.
The worst are the skull crawlers, you really don't want to drink a brew with them in it.