Cirrhopetalum Elizabeth Ann 'Buckleberry's leaves turning yellow

[Anton]

Hi there, hope you can help. I am new at growing orchids. I have had this Cirrhopetalum Elizabeth Ann 'Buckleberry' for just over a year. It has been growing fine and making new shoots up till now. One of the leaves have just turned yellow(see attached photos), and I think this is the first sign that it is not happy. I understand some people grow it in a pot with sphagnum moss. Is this better than growing it on a piece of wood,or do I just have to give the roots some sphagnum moss. Any suggested fertilizer? Is my location alright? (see attachment-it does not get direct sun). Could it be over or under watering- I spay it once every second day. Any help would be appreciated.

Thank you
Anton