should my sour pickles be sealed while pickling? I'm making sour pickles. A lot of recipes say that the lid should be loose or upside down so that the pickles have room to "breath". I keep the jars out, often coming into contact with light from outside.

Does leaving the top on loose pose an increased risk of botulism? I understood that botulism bacteria multiply rapidly in an anaerobic (no air) environment.

The brine is pretty darn salty (1tb : 1cup of water), and it contains no vinegar.
Those pickles create their own acid. Wild bacteria that can handle the very high salt content produce lactic acid, thus preserving the pickles.

Botulism won't grow in that much salt and with how acidic the pickles are going to be when they're done. That's kind of the point of pickling in the first place.

The instructions say to leave the lid loose because the fermentation may also produce gas and it needs to escape. You don't want a half-fermented-sour-pickle bomb to go off in your kitchen.