@StripeyYena I think Argon is particularly vulnerable to sneak attacks like this when circulation is bad. Oxygen collects at the top, then it finally reaches a threshold, it looks like Oxygen suddenly went through the roof, when actually it’s been building for months.
This is my working theory, since I’ve had this exact scenario. Everything seems fine, then suddenly Oxygen is crazy for no obvious reason. I really need a fan in the box.