Were born. When our starters came into the world, they were 100% rye flour starters. Today is graduation day from rye flour to all AP flour. Today, our starters become toddlers.
When we woke up and took a peek at them, we probably noticed they were topped with a layer of tiny bubbles
and we may have even noticed that hiding just underneath that top layer of bubbles was a layer of hooch!
This probably was your first layer of hooch.
If you didn't have a layer of hooch, don't worry. It doesn't mean anything is wrong. It just means your yeasties aren't eating through the flour super fast. You will get some sooner or later. We want to stir any hooch back into the starter. This will make the starter very foamy and frothy.
After feeding the starter its first full 1/2 cup feeding of all AP flour, your starter will get those big roiling bubbles we've become accustomed to with the rye flour feedings. What you may notice though is the "rise" doesn't seem to be as vigorous. It may take it longer to get the roiling bubbles.
After we have a second feeding of all AP flour there will be few if any huge roiling bubbles. This is normal as the starter adjusts to AP flour.
Also notice how different in color the starter is from the first day
A heads up, we are now entering a more placid and less active period the next few days while the starter finishes digesting the rye flour and begins to get used to an AP diet. Between now and through Day Seven and possibly until Day Ten, you may notice your little yeast friend isn't a lively as he/she has been. Don't worry that your starter has died, it's just going through a phase.
Just like a toddler gets used to solid food...