Help with an heirloom - repeating a success

[Stefan Petersen]

Dear Orchidboard

Last year I got some excellent advice and revived a dendrobium, which I thought was a goner. That meant the world to me since the orchid was one of a very few things I inherited from my grandmother. It even blossomed after a few months tender care

The other thing I inherited was a phalanopsis which also seemed to be getting better after being on the brink with only three small leaves. But now I see a dark green/brown area on one of it's leaves. It got me worrying if it is somthing that might be an issue.

Do you have any idea, what the dark green area is and how I should treat it?

I keep it in a huge south facing window, but I have have drawed a light curtain in front of it so it isn't hit by direct sunlight. I live in Denmark where the sun atm rises at 05:00 and sets at 21:20. I cant decide if the sun is to intese through the curtain when the sky is clear or if it is too dark, when there are clouds in the sky.

I give it water every two weeks, where I put it in a clean bucket with water for an hour. Last year I was watering it more frequently this time a year (every 8th day). But due to illness and work I have against my wih kept it on the winter routine where it is only every two weeks.