So the yellow spots are concern usually of pest in my experience but you have a lil more going on so lets see. If its a bottom fan leaf than its normal but something just not right. If its near the top your right it could be wind burn. Fan should always remain on unless your room as an advantage i.e. you live in a colder climate so you can save some power and run it for an hour every other hour or something up to you. You also need to dial in on your silicate and calmag. And last but not least the spots are concerning. Pick the leaf you notice with this and scope it to ensure its not pest and eliminate a possibility. Hope this somewhat helps.