Three days ago I went to make a 1L starter and I ended up with about 800 ml because I boiled a bit too long.
I pitched the yeast and let it go. I am wondering if it would make sense to add a bit more starter wort (a cup is about all that will fit) to bring up the volume and get a bit more cell growth? I am assuming that by the this point the yeast is done reproducing and is just fermenting the wort, so I don’t know if topping it off will give me more yeast or just more fermenting wort?
Assuming that the yeast has completed eating all sugar in the 800ml, I would put the container in the fridge overnight.
Then pour off the liquid and put some fresh wort in the flask or whatever container you used to make the starter.
If the timing is right, you can just pitch the whole thing when it is actively fermenting or wait until it completes the process, cold crash again, pour off most of the liquid and pitch the yeast.
+1 to this. If you have enough time before brewday you can let the new starter ferment, cold crash again and on brewday take some of your fresh wort and replace the starter liquid with it. I collect some of the first runnings, boil 15 minutes and cool. Once it’s cool I pour off the old starter liquid and use the new stuff. By the time I’ve finished the sparge and boil my starters are going absolutely nuts, and the wort used is the same as the wort in my beer.
Nice! That seems like a great process! One more tool in the tool box. Thanks.