Stepping up a starter

[Paramecium]

In the past I have stepped up by decanting off the 1 liter beer/wort layer after a couple days on the stir plate after it has settled out for a few hours and then made 2 liters of fresh wort, cooled and poured into the flask on the small yeast cake from the first liter. Is this the correct way to go about it or would simply adding 1 liter to the existing starter do just as well?

 

[avidhomebrewer]

I would prefer to decant. Give the yeast more oxygen in the water to work with and more wort to consume.

 

[Belmont]

Yeah the way you're doing it is better for the yeast. Fermented wort is beer which has alcohol which isn't good for yeast. It's not an oxygen thing though. Fresh wort has no oxygen in it other than what it picks up from the pour into the flask. Oxygen comes from the stirring. So you'd get the same oxygen either way. You'd just have less alcohol in solution and more nutrient and sugars for the yeast to get stronger.