As tempted as I am to blame the house or the new location, that of course opens the door to more sinister questions like is it even safe to live in it?
I would hope that this part is OK.
I'm actually not running carbon right now. I can always put some on though, guess it can't hurt. I'm sort of wondering if running UV might be something to look into.
Old tank syndrome is also something I've thought about. I think that this is a mix of both "documented and explainable buildups/depletions" and "something we just throw out there when we can't come up with any other plausible explanation." Ultimately there is so much going on at a level we can't really perceive it's really hard to come up with simple one-tiered approaches to problem solving.