Just bought the PH04 unit last week. I've been running the purifier and humidifier on auto mode. Run the unit only at night to morning when I'm in the bedroom (totalling ~9 hours). However it looks like the water is depleted ~70% by morning. Was under the impression it should last about 36 hours. Confused why the water is depleting that quickly. Humidity level is around 43% so don't see that as an issue.