To be safe I would take the diffuser out of the tank at night, at least for a while until you get a handle on things. As mentioned by @Darkblade48
the drop checker will give you a good visual reference that the co2 isn't at crazy levels by noting the color which should be green, not yellow. Many diffusers double as bubble counters. You can also just see how many bubbles are coming out by removing the diffuser from the tubing.