A got this plant a few weeks ago, and it was doing pretty good for the most part. But lately some of the leaves (mostly older growth) have been getting yellow and brown. I have the correct type of soil and my pot has a glaze so there’s no problem with that. I also use distilled water, (I make sure I water it every day because that’s what I was told to do, but now I think that might be the problem. In the day I have a very sunny window and it gets about six hours of sunlight. I’m really not sure what I’m doing wrong, and wondered if anyone had any ideas?