I have a large thriving bird's nest fern that I had in the window at work. It was kept at a constant 68 degrees F and received bright reflected light in the afternoons and I watered it once a week with distilled water. When I retired last month, I brought it home. Now the fronds are turning yellow with dark splotches. The location I have it in now gets a little filtered sun in the morning there's nothing I can do about the lighting conditions), is fairly cool (60 to 65 degrees F) and watered with home tap water. Our water here is fairly hard with high levels of haloacetic acid although I usually draw a few gallons and let it sit a few days before use. What could be causing this and what can be done about it?