One of the big variables in the world of bread starter recipes is moisture. Some can be extremely wet, up to 60% water, others somewhat dry, in the realm of 35% water. Is there any practical difference between them?
For the purpose of getting a starter culture going, the answer is no. Though I’ve had better luck in my starter-making career with wetter starters (as I said, I prefer a 50-50 mix of water and flour by weight). However once you’ve got your starter going, the degree of moisture will impact taste.
How so? Well, while any starter you make at home will contain the same mix of microbes (and there can be dozens, even hundreds), the degree of hydration will affect their proportion. Some types of micro-life prefer a wetter environment, some a drier one.
Among bacteria, the prime movers behind a sourdough starter’s flavor, it’s been found that acetic acid producers tend to like things on the dry side, lactic acid producers prefer things wet. That said, if you like a tangier bread (which is what more acetic acid will get you) you probably want to keep your starter — as well as your finished dough — drier. If a mellower flavor is more your thing, keep the moisture high.
Of course all sorts of factors from hydration to storage temperature to the rate of feeding can have an impact on a starter’s flavor. Which is why I suggest lots of experimentation.