The lowest safe amount is 1.5% salt for the total weight of everything else. So, for example: if you're fermenting 300g of peppers and cover them with 200ml = 200g of water, you should have at least (200+300)*1.5% = 7.5g salt.
When preserving veggies I usually do this by weighting the veggies and water together then adding the salt, instead of making the brine separately. Salt dissolves easily anyway.
Hmm, I have been making the brine seperately, mostly because I'm worried the salt won't get distriibuted enough if its just heaped on at the end. That isn't an issue?
From my experience, that isn't an issue; eventually the salt at the top dissolves, and since brine is heavier than water it sinks, so it mixes itself. (Sometimes a gentle shake helps too.) I do it this way because the resulting salinity is a bit more consistent, than when using a brine with a fixed salt/water ratio.
A third option is to eyeball the amount of water you'll be using, weight it, do the maths on the amount of salt you'll need for the water+veggies, make the brine separately with that water, then pour it over the veggies. It takes a bit more work, but if you're worried about the salt not dissolving properly, it's a good option.
I've had great success using 2.5% salinity for most batches. My understanding is that 2% is about the bottom range of what’s safe. You might try salting til it tastes good, figuring out what percentage that is, and try a ferment at that salinity. If it doesn't work you’ll know.
Okay, I'll try 2.5% next. It'll probably taste great at that level anyway. Thanks!
2% by weight (not volume) will work just fine.