Went away for a week, came back and my starter has a layer of liquid on top and barely any bubbles. It smells sharp but not off. Is it salvageable or do I start again? It's about two years old and I'd hate to lose it.
That liquid is just hooch — totally normal when it's hungry. Pour most of it off, discard all but a spoonful, and feed it 1:1:1 (starter:flour:water) by weight. Keep it somewhere warm and feed twice a day for two days. It'll bounce back, two-year-old cultures are tough.
Agreed. If it's really sluggish after a couple of feeds, try a pinch of rye in the mix — wakes mine right up. Don't bin it yet!