Dry starter reactivatio

[ooops, I buggered my comment, fixed below]

I would need to know the exact amounts you start with and what the instructions say for feedings.

Most starters are fed with either 1/2 water and 1/2 flour or 1x water and 1x flour.  So, if you have 50g of starter, one method has you adding 25g water, 25g flour, the other method has you adding 50g flour, 50g starter.  Usually the feedings are based on how much starter you currently have.

Also, I would probably recommend at least a couple feedings before using the starter for baking.

Rye flour works well with any starter and can provide the nutrients to get a new starter off to work. The consistency will probably be on the thick side so sprinkle a little flour over the top of the starter paste so you can observe for yourself that your starter has activated when cracks appear in the flour topping. After a couple refreshments, you can easily switch over to white or whole wheat flour if you wish or keep the starter as a rye starter.

Remember to add your ingredients by weight rather than volume.

Welcome cef!

I wouldn't worry too much about what amount of starter is left to keep. Even just a spoonful is okay, so whatever is left in the container is normally good enough, as long as you don't scrape it all out with a spatula.

(Unless you actually mix the dough for your bread in the container you have the starter in, then you do have to remember to take a spoonful out before you start adding the ingredients!  I normally keep the starter in a small container that holds max 250g, if I need more starter, I will "build" in a separate container.)

Caveat: I'm pretty new to this and have only worked with a self-made starter, never a dry/purchased one.

Mike

You needn't make refreshing your starter so complicated. If you've got 50g left over, you can add 50g water and 50g flour if you like. However, you could also add 45g of water and 60g of flour and get a lower hydration level culture. You could add 100g of water and 100g of flour if you like. The thing is that you need to have a hydration level in mind (flour/water) and how soon will you need the desired amount of starter for your next bake.

100% hydration starters will mature faster because the yeasts will be able to move about faster in the culture. They will also consume the available food faster so you need to watch for the maturity of the refreshment closely. Hydration levels of less than 100% will mature more slowly but will also be advantageous for that fact. If you want to refrigerate your starter, a less than 100%, say an 80%, starter will be able to go longer without refreshment.

You will need to learn about hydration of your starter eventually but keep in mind that starters are amazingly resilient. They will give you the opportunity to experiment and learn. Short of using up all your starter or killing off your starter by leaving it in a heated oven, or something else that's deliberately meant to kill the starter, there's not much you can do that's fatal to a starter.

Experiment,learn by experience, and have fun.

I added the initial 3/4 cup water and 3/4 cup flour to my dry starter culture and left it in the oven with the light on to provide warmth. Bubbles are clearly visible and incubation is proceeding nicely. Tomorrow,  I need to add more water and flour as in step 2 of the activation procedure. Do I first remove 1/2 of the young culture before adding the additional flour and water just as if I was "feeding" it or do I the the new flour and water on top of the full amount of the young culture? The included instructions are somewhat unclear. I am grateful for any assistance.