Hey, really cool you’re diving deep into lacto-fermentation! about your question on X and Y, basically, X is the weight of your veggies or fruit (like grapes), and Y is the water you add. you add salt equal to 2% of the total weight of both combined (grapes + water). that way the brine is just right for the bacteria to do their thing.

And no worries about the air purifier, lacto-fermentation relies on the good bacteria already living on the veggies and floating around normally, so it’s not like you need bacteria from the air to start it. keep the purifier on if you want.

Your onion ferment sounds delicious btw, might try that soon