Quick answers
What's the difference between 2% salt sauerkraut and 3% salt pickle brine?
The 2% sauerkraut is 2% of the vegetable weight (self-brining); the 3% pickle is 3% of the water weight (you add separate brine). Different totals land on the vegetable itself.
Is sea salt, pickling salt, or kosher salt best for fermentation?
Any pure salt without iodine or anti-caking agents works. Kosher salt varies by brand (Diamond Crystal weighs about half as much as Morton per tablespoon), so always weigh.
Can I use table salt?
Only if it's non-iodized and has no anti-caking agents. Most table salt has both.
Why does my sauerkraut need only 2% salt but pickles need 3%?
Cabbage is about 92% water and releases that water into its own brine, so 2% of the cabbage weight ends up in the brine naturally. Cucumbers release less water and sit in added brine, so the brine itself needs to be 3%.
What if my water is very hard or soft?
Mineral content doesn't change the salt percentage, but very hard water can add bitterness. Use filtered water if your tap water tastes chalky.