After Fermentation Issue! Or Infection?

[my98xc600]

Hey everyone I have a minor issue that I'm looking to understand what's happening.

The issue is not so much with mashing or fermentation its after the ferment is complete. I've been doing all grain bourbons for a few years now with excellent results (thanks to all the info on this site). After the mash is complete my S.G is around 1.070, I use Safe Ale US 05 and ferment on the grain at 65-70 degrees for two weeks. The final gravity always finishes at 1.000. After fermentation I separate the grains and let the liquid clear and settle for a week. This is where the issue comes into play.

Around the 5th day just as everything is settling out nicely, it start's to, what appears to be a very slow ferment again. This stirs everything back up into the cleared low wines. It kinda defeats the purpose of clearing it, but I run it anyway because 75% has settled out.

I find it hard to believe its any sort of fermentation when it finishes at 1.000. Will a lacto infection cause this to start bubbling? The reason I ask is, if I leave what has settled out and a bit of the low wines after two weeks I get what appears to be a nice lacto infection and it has an awesome fruity smell to it. and shortly after that develops the bubbling stops again.

So, will a Lacto infection causing this? or why is it starting to "ferment" again a week after I start to clear the low wines?

Thanks.

[Twisted Brick]

I believe your bubbling is trapped C02 releasing from the trub as fines settle. At this point all fermentables have been exhausted and its time to strip.

[NormandieStill]

A quick terminology point: what you have pre-strip is best called either a wash, or in the case of whisky, a distiller's beer. Low wines are what come out of the still during a stripping run.

Your beer can ferment below 1.000 because of the effect of alcohol on the hydrometer (an ethanol / water mix has a different density than pure water). If you're racking before it's finished then it may just continue fermenting.

Are you squeezing to separate the grains and then letting the resulting mix settle? I had some success racking off the clear first then squeezing what was left which could settle in smaller containers.

The photo certainly looks lacto-like but I'd be surprised if it's that that's stirring everything up.

[my98xc600]

Are you squeezing to separate the grains and then letting the resulting mix settle?

Yes, I run everything through a brewers bag and squeeze it with the mop wringer. Fermentation stops in the fermentation barrel and after squeezing and transferring everything into the settling barrel is when it starts again a few days later. Could It be posable I'm squeezing out some sugar?

This time I'm going to leave it a week longer after fermentation stops and see what happens.

[Demy]

It looks just like an infection.

[NormandieStill]

What makes you think the fermentation has stopped in the first place? I'd be very surprised if you're squeezing so well you making sugars freshly accessible to the yeast. More likely, they were still fermenting slowly and you just shook everything up a bit when you squeezed it all. If you want to be sure it's finished, it's not enough to take a single reading; you need to take two or more, at least two days apart and see if the gravity has changed. As long as it's changing, the yeasty-beasties are still working hard and you can just leave them alone to do their thing.