I'm planning a Bavarian Hefeweizen and I read, to keep it real, one should use wort ("speise") to carbonate it. Has anyone got some experience as to how much speise to use or how to calculate an adequate amount?
A brewer friend of mine does this regularly. I quizzed him about it and he advises pulling 2-3 quarts out of your original 5 gallon batch, into a sanitized jar that sits in the fridge while fermentation takes place.
You can do this right out of the boil kettle, and into a pre-heated glass jar. Top it, let it cool on the counter, and put it in the fridge while fermentation takes place.
Try this link to Kai Troester's wikisite:
Sugar for Carbonation
I can't just post an answer because its dependent upon the temperature of the fermented beer (residual CO2) and the gravity of the speise. I also don't know to what volume of CO2 you want to make the resultant beer.
I don't know how much to use but here's how I would go about figuring it out:
I generally use corn sugar to carbonate, I believe (going off the top of my head right now) it's something like 1 cup of sugar added to 3/4 cup water and boiled to sanitize/dissolve.
So I'd mix the sugar and water together and take a hydrometer reading and then mix up some wort with the same gravity and then mix the same volume (as the sugar water) of that wort into your beer to prime for carbing.
There's probably a way to use math to figure out how what the gravity of the sugar water would be and to figure how much DME to use to reproduce it that reading but I'm not that technical.