Feeding 3 through 10: Repeat the process as stated above every 12 hours for a total of 10 feedings (5 days). By day 3, you should see bubbles and aeration after 12 hours. Right after the tenth feeding, transfer the starter to a mason jar (anything from a 12-ounce (340ml) to a 1-quart (1L) jar will work well) and let it ferment there for up to 12 hours or until it’s bubbly. The starter is ready to be used. For storage and feeding info, click the tip below.
You can store your ready-to-use starter in the refrigerator where it will keep indefinitely. You should feed your refrigerated starter at least once a week to keep it healthy; ideally, use it every 2 days. The more you use your starter, the healthier it will be. If you don't make bread often and keep your starter in the fridge for days at a time, it will likely not be bubbly and active enough to use without refreshing it a day before you plan to use it. Longer periods of inactivity may require two feedings before use.
To make the Country White Loaf, Aran suggests keeping a base of 150 grams of the brown rice-teff starter; feed it 130 grams of superfine brown rice flour plus 20 grams of teff flour and 178.5 grams of water (you can round up to 180 grams). Shake or whisk vigorously and let ferment at room temperature. If you're not going to use it right away, return it to the fridge.