Detecting mold with a blacklight
What's the humidity level in the room? I'd go get a $12 humidity sensor and see what you got. My understanding that mold can grow >= 60% RH, though there are other factors (e.g. moisture will condense on a cold wall with a lower relative humidity). You may need a dehumidifier if you're too high. Of course that won't kill the mold but will keep it from growing.