Starter turns to junk after 2 weeks
I've had basically the same problem for three tries of making starter. Here's what happened the last time:
Day 1: Mix equal parts locally sourced whole wheat flour and orange juice
Day 2 & 3: repeat
On day 4 the starter is super active. So much that I can bake a round loaf using just what I would've discarded. It rises beautifully and (aside from the hint of orange juice) is delicious. The rise is as good as anything commerical.
Day 4: feed 1:2:2 starter:flour:water by volume. I use filtered water that's been sitting out for at least a few hours. The flour is a 3:1 mix of King Arthur AP and the same locally sourced whole wheat from the Farmer's market that I used to start the starter.
Day 5-8: repeat
On day 8 the starter still looks beautiful. I bake another loaf using 400 g 100% hydration starter, 300 g King Arthur AP flour, 125 g water and 10 g salt. The loaf rises beautifully, gives great oven spring, all is happiness.
I leave the starter at room temperature, feeding daily, discarding unused portions of starter. By day 13 however, it's gone from looking like a beautiful poolish after feeding to smelling foul and having tiny bubbles without really moving at all after feedings. On day 13 I try making a loaf using the same formula I used on day 8. This one doesn't rise at all, even after 12 hours at room temperature with me checking on it every couple hours. I try to bake it anyway late that night, but it is just a snotty mess of dough. The product tastes sour, but is basically a hockey puck.
Basically the same thing has happened the last 3 times I've made starter. Is it salvageable at this point? Is there something I'm doing wrong here? I suspect that the bacteria are beating out my yeast, but I can't figure why or how to stop it. Any help would be greatly appreciated.