To expand on my previous post.....take a look at these. Five days ago, I activated commercial starter. At the same time, to test a theory, I mixed up some white flour and water only. Commercial starter on the left. On the right, a mix of the same white flour and water.
Both went nuts after 24 hours, but the flour and water developed a middle layer of some kind of gunk.......NOT hooch. Smelled great though. Kind of a cross between butter and butterscotch. A day later, it went dead and never recovered.
The commercial start has been going great and getting better every day. In fact, today at noon I mixed up some dough for a loaf to bake tomorrow. After a 6 hour proof at room temperatures, it looks like this:
This will get baked in the morning.
Yes you can make your own, but none of the starters I made behaves or tastes like this. No more expensive than they are, you will save a lot of time and effort buying a starter, and have a better product to boot.