New starter (about 3 hours old) already more than doubled!
I'm completely new to making sourdough (and a little less new to baking in general), so I need help (I think). About 3 hours ago today, I began developing a starter using a recipe from a baking book. This recipe calls for combining 1 package of active dry yeast with 2-1/2 cups lukewarm water, leaving it to dissolve for about 15 minutes, and then adding 1-1/2 cups flour. The mixture is supposed to be covered and left to rise in a warm place for at least 24 hours, but preferably 2-4 days before using, yielding 3 cups of starter.
As of right now, the starter is almost 8 cups and bubbly, and looks like it's continuing to rise. I had to transfer it from the original porcelain container in which I had it, to a much bigger (metal) container, as I don't know how much more it'll grow.
My question: Did I make some sort of mistake? It seems like the starter is growing too fast and too much....At least, I wasn't expecting it to grow so much, so quick. And the recipe did not call for mixing the ingredients in a large container...so I'm thinking that the starter is not supposed to do that. If I made a mistake, how can I correct it?
I know that this starter is young enough that I could afford to throw it out if needed, without losing too much in terms of ingredients or time spent on it. However, I'd rather try to save it, if at all possible. Thanks for your help!
EDIT: Just wanted to let you all know that the poolish did stop growing the next day, and in fact I saw a little separation. I freaked out a bit, as I thought I had killed my little guys; but instead of bugging you guys right away with questions as to what to do, I decided to try to save it by feeding it some AP flour to see if it worked. It did, though the bubbly-ness and volume of the original didn't come back fully. The day after, I baked some very very good tasting white bread with pretty good texture, following the recipe in the same book for sourdough (I guess I should have expected that it would not taste like true sourdough, but the bread came out pretty tasty nonetheless; and as it's not true sourdough bread, I have decided to call it "white bread"). It was a little too crunchy at the top of the crust, but other than that, I was very pleased. Definitely the best loaves I've baked so far. I saved some of the poolish starter (can I call it that??) for later, so we'll see if it behaves next time I use it.
The very same day I baked the white bread, I also started a true sourdough starter following Gaaarp's recipe. Today it's day 4, I believe, but the starter has not doubled in volume...So I'm waiting to see how it develops before I feed it or do anything else to it. I bought some unsweetened pineapple juice just in case... :)
Thanks everyone for your comments. If you have any good recipes for breads that make use of poolish, please post them (or a link to them) here. Noobs: if you'd like to use this thread to ask questions about your own poolish or starter, please feel free to do so.