Discoloured leaves
 

The old leaves on my Brassia and Catasetum are discoloured. I know they yellow and drop leaves naturally, but the leaves aren't exactly yellowing so I don't think its that. The new leaves are fine. Is it some kind of mineral imbalance? Maybe too much light? These are the only two orchids I have that are like this, and coincidentally they also get fed the most and receive the most light.

http://imgur.com/a/ilrf1AF

Edit: Weird, the photos don't show. I thought imgur works on here? I'll just post the link I guess

discoloured leaves - Album on Imgur

Could be ORSV or simply a nutrient deficiency issue.