i keep reading how everyone uses vodka is their airlocks, i used 10%-ish bleach. then i read about suck back during fermentation. i was under the impression that co2 would prevent any suck back of the liquid in the airlock. should i not be using bleach in my airlock? 10% isnt very concentrated and i do have 5 gallons of beer, so i doin't think a drop would ruin the batch (or kill me when i drink it), btu just curious as to what you thought. when does suck back occur?