I do plain fermented carrots too. I use a bit less salt for them because they aren't as "juicy" as, say, cucumbers. Probably 4 tbs per half gallon of water. Length of ferment depends on the temp in my house. Also depends on how you cut the carrots, sticks will take longer than shreds. You can start tasting them after a few days and refrigerate when they get to the tartness level you like. I never put a lid on them til they go in the fridge, so mine don't get fizzy. Sounds kinda fun tho, lol.