Stop the humidifier as your humidity level is too high during the night ( good for veg ) , don't stop your vents during the night as you humidity is higher at that moment and the HPS are not helping as it's well known that the RH light on is way lower than during the night when using an HPS , it is due to the heat emited by the HPS. You question should be : how do I get rid of the high RH that occures during night time when the lights is off ?
To push the air ( and humidity ) out I recommend a air extractor
And water your plant just beore the light turn on and not when the light is off to limit the humidity level to raise during night time