12 Hours into my first starter - more questions

Hi,

I made my first yeast starter last night (Wyeast 3787 - Trappist High Gravity). I'm using a 1L flask, and the starter is around 650ML. I know this is a small sized starter, but the Trappist Ale I'm brewing should have an OG around 1.053, and the starter calculator I used says I should end up with 100-130B cells, which should be plenty.

I pitched the yeast around 6:00pm, and by 8:00pm I had a steady stream of tiny bubbles and some nice slow airlock activity. This morning it was getting a thin layer of bubbles on top (no crausen), with active bubbles and slow steady airlock activity. It had already formed a fairly good yeast cake on the bottom, so I swirled the flask pretty good to suspend all the yeast. At the moment, this seems to have halted almost all bubbles and airlock activity - I assume that's normal?

I plan to brew on Friday, and I want to refrigerate the starter beforehand so I can decant some of the wort off. I know there won't be a lot in a starter this size, but I've read a couple of posts that say this yeast creates a fairly nasty smelling starter.

My question is, for a starter this size, and the activity I'm currently seeing, at what point should I put it in the refrigerator?

Thanks as always for the great help!

Don´t put an airlock in your starter you want oxygen in there so yeast can multiply, if you don´t have an stir plate swirl your flask everytime that you can. A little aluminium foild on top should do the trick.
With that much yeast and that little liquid your starter shoul be done in 24 hs, when you think it´s done you can put it in your fridge. on brew day take it out from the fridge so it gets to room temp, decant all the liquid you can leave a little swirl everything and pitch.
Check mr malty or yeastcalc for proper pitching rates.

It is entirely possible that it's completely fermented out. However, since your intention is to use it for a Friday brewday, you can wait to refrigerate until Thursday night, and pull it out on Friday AM to warm up to room temp before decanting and pitching the slurry. Your timing should be just fine on this, that's pretty much what I do for every starter I make (i.e. three days before brewing).

However, I think there's one difference I do want to call out: you referenced using an airlock. Typically, you don't use an airlock on a starter, I'm assuming you're not using a stir plate of any kind, and are simply making a "small batch" as a starter? If that's the case, then I can see why you'd put an airlock on it, but I want to call out that you need to make sure that you adequately oxygenate the starter before putting the airlock. Oxygen is a key ingredient to yeast colony growth, otherwise the existing colony will just eat the sugar, and your colony size is going to be very similar to whatever you pitched into the starter, likely lower due to life cycle decline.

Sorry, for the delayed response, I've been at work all day, where the internet filters keep me from visiting "bad" sites like this one!

As an update, the starter began sending up a few streams of bubbles again before I left for work this morning. When I got home, it had a thin layer of bubbles on top, a good yeast cake on the bottom (seemed bigger than last night's, but maybe I'm just hopeful) and was actively bubbling again. I gave it another good swirl to get all the yeast suspended. Just like this morning, the swirl stopped all visible activity, but I'm seeing a few tiny bubble streams now.

That's interesting about the airlock. I've read several posts, blogs, etc, about starters the last few days, and while some mention tin foil, most of them recommended airlocks. After I cooled the wort, I transferred it to a sanitized jar that I shook the heck out of. I then added the yeast and gave it another good shaking before I transferred it to my flask, so hopefully it got plenty of oxygen mixed in.

I'm already thinking about buying (or building) a stir plate for next time. I've also seen foam plugs for starters. I assume those work pretty well to allow air exchange while keeping anything from getting in the starter?

So it's best to leave it out until Thursday night? Do you want the yeast to really get going and then stop it, or pretty much let it do as much as it can with the starter wort? The information I'd read about starters is all over the board. Anywhere from only letting it go 12 hours to letting it go for days. I realize some of that depends on the starter size, yeast, whether you plan to refrigerate first or just pitch, etc. That's a downside of the internet - plenty of information, but not always good information.

Thanks for providing help I can trust!