Originally Posted by Markf
The vinegary smell is normal. Keep feeding it. This can happen if you use a different flour for feeding it. If it turns a dark color or gets mold on it...toss it, start over. It may get a clear liquid on the top. This is called hooch (alcohol). Pour it off before feeding. This is a sign that you are not feeding it enough.
I keep mine in a large container in the fridge. It is traditional San Francisco sourdough. I keep the container sealed to prevent other yeasts in the air from mixing in. Its now over 25 years old. I feed it weekly, equal parts flour and water.
I'll admit that I started the first feeding with AP flour. I switched over to bread flour like I should. No mold and I do have some liquid on top. I've been stirring the hooch into the slurry before I pour off.
I've been feeding equal parts flour and water too. If hooch is a sign of a lack of feeding, should I be adding a pinch more flour? Maybe 60:40?