I've burned plenty of scented candles, and also my Yankee Candle scented oil burner, plenty of times in my living room with no issues. My 45 gallon community and 55 gallon discus tank are in the living room, and the kitchen/living room wall has sort of a "window" with a ledge which is where the scented oil burner is. My open-top SW pico reef is in the kitchen about 4 feet from the oil burner. That tank is so small that if it were really an issue, that would be the first to go. I wouldn't worry about it.