I discussed this a little with frank as well. I'm not sure what the actual scientific answer would be on the effects of barometric pressure on a fish tank so i defiantly wouldn't count this out. My thought initially was this, there are more swings in temp when the pressure is changing (front coming through) typically its our temp dropping. if the temp is dropping and the furnace (what we thought may be the issue) is kicking on more because of it there would be a def correlation.This is going to sound crazy, but I feel like I have more problems with this whenever we are experiencing a lot of barometric pressure changes. As soon as everything stabilizes this problem seems to go away. I'm not 100% sure if there's an actual correlation or not, just my brief observations