Sourdough Starter Very Runny I think I'm having a problem making a sourdough starter.
I'm using the technique from King Arther Flour
I started with 113g of whole wheat flour and 113g of water.
Every day, I retained 113g of the starter and added 113g of AP flour and 113g of water.
On the third day I started doing that twice a day.
After a week, I went back to once a day.
It seems to be fermenting. It gets bubbly, has a fruity, sour, floury smell.
The trouble is, it is extremely thin. Like crepe batter thin.
It bubbles, but doesn't &quot;double in size&quot; because it's really really thin. It doesn't look like any of the pictures.
What am I doing wrong?
Edit to answer questions in comments:
I'm in Manhattan and it's been very warm lately. With air conditioning, I would guess room temperature is mid to upper 70s. Maybe warmer.
I guess the flour is coarse. I no longer have the packaging, but it's just whole wheat flour from the supermarket. Probably Gold Medal.
The starter doesn't rise at all. It's too thin to hold any kind of structure. It does bubble and what not, and develops a layer of hooch. There is clearly fermentation happening. There's activity within an hour of feeding.
The water is just cool water from the tap. It's NYC water with absolutely no chemical smell.
Actually, reading further on the link you provided I found this:

Why does this starter begin with whole-grain flour? Because the wild yeast that gives sourdough starter its life is more likely to be found in the flora- and fauna-rich environment of a whole-grain flour than in all-purpose flour. What if all you have is all-purpose flour, no whole wheat? Go ahead and use all-purpose; you may find the starter simply takes a little longer to get going. Also, if you feed your starter on a long-term basis with anything other than the all-purpose flour called for here, it will probably look different (thicker or thinner, a different color) and act differently as well. Not to say you can't feed your starter with alternate flours; just that the results may not be what you expect.

So perhaps your starter is just thinner because you're using AP flour. If you can, try to add rye or whole wheat to your feedings. That should make the starter stronger.
Another thing I'd try is to wait longer between feeding and check the starter's behaviour: how long does it take to rise? How much does it rise? Start feeding after the peak (when it starts going down) and see if that changes the behaviour. If you see hooch it's past feeding time, try to feed your starter sooner.
You can also try using less water (instead of 100% hydration lower it to 80%) maybe there's not enough gluten to keep a strong structure at a higher hydration level.
In any case, make sure you use water that is warm enough (24-30ºC) and be patient! It might take longer to get your starter stronger (it took me 2-3 weeks the first time, with the wrong kind of flour).