I'm new to this and have noticed that in some cases I get a crackling and steaming sound when vaping, similar to using a steam iron. This doesn't really bother me but I'm wondering what is going on. I assumed it was the carto (I'm filling myself) but I can move the same carto to another battery (different supplier) and not get that sound. I am using lower resistance cartos at this point, based on what I've read on this site. What gives?