Ok - so you've got a live, bubbly and active starter - done, right? Not quite - you need to keep it alive so you can continue to use it. It's almost like a child, so a lot of people name their starters, myself included.
The general feeding and maintaining of your starter is relatively easy - you're basically going to be following the same procedure that you did daily when you were culturing it - discard and add more "food". Your schedule for feeding your starter, however, will depend greatly on how often you plan on baking - are you going to be baking almost daily? On weekends only? Not much at all?
If you're planning on baking almost daily, like in my house, you have to feed your starter at the very least once a day, I've been splitting and sharing my starter to the neighbourhood, so I usually have several jars going at the same time. The idea is to discard around 3/4 of your starter, and either use it for other goodies (more on that when I have the time to make the post, but in our house, we've done pancakes, waffles, tortillas, crumpets, etc. from all our discard!), or you can split it and feed it to share with others, or...you can actually discard your discard. But don't do that - it's wasteful, and such a shame!
I have no particular "recipe" for feeding my starter, since it's completely dependent on if I'm splitting into multiple jars for people. But as I said, discard about 3/4 of it - if you're going to keep it for other baking projects, you can keep it in the fridge - some recipes call for unfed starter so you're golden. What I usually do with my feeds is eyeball what I need to replenish the 3/4 that I've gotten rid of...on a 1:1 ratio - 1 part water (once again, filtered! We don't want chlorine, it kills your yeasties), and the other part flour - you can use a mix of AP, whole wheat and rye, or any one of them if you don't have it on hand. One thing to note though - rye makes your starter VERY active...so make sure you always leave room for the inevitable bubbles. When using rye, only use it as a small percentage of your total flour - no more than 20% or so.
If you're not baking every day, you can keep your starter in the fridge, and feed using the same ratio once a week.
If you're baking every day, keep it out and covered (the lid to your jar is fine, but don't screw it on...just in case you have a sudden explosion of growth and the gas needs to escape).
If you have discard that you don't have time to use, and your fridge is full...one super useful tip I found is from Amy in the Kitchen - she spreads her extra discard out on a sil pat, lets it dry, then breaks it up into little pieces and stores them in an airtight container. You can give out your pieces of dried sourdough to share with friends, and when you need it, you can re-hydrate and follow the discard/feed schedule until it's active again for your baking! Here's the link: https://amyinthekitchen.com/sourdough-starter-maintenance/
Some troubleshooting FAQs:
If you see lots of foamy bubbles on top, your starter is HUNGRY. Feed it.
If you see a layer of liquid on top (can be a bit gray) - don't freak. This is a byproduct of the fermentation process and is well...alcohol. And it has a name: hooch - I kid you not. Also - your starter is HUNGRY. Feed it.
If your starter has a pinkish or orange tint to it, your starter is done for. That's mold. DUMP IT. And get in touch with me for another starter, or grow a new one!
No activity? You may be able to revive it with the same process you used to start your culture. If after 3-4 days of daily discards and feedings you still have no activity? Sorry. DUMP IT. And grow a new one or get some from me!