black leaves on my orchid, help
 

hi,

I received this orchid 3 months ago, and a tip of one leaf had a couple of black spots. Now, the blackness has spread over all leaves but one. I thought the pot it came in was too small because the plant was nearly falling out, but I am afraid the current one might be too big. Is my orchid overpotted or is it infected? Any advice would be greatly appreciated, since this is my first orchid.
Thanks!!

It's a tad hard for me to tell from tiny, out of focus photos, but to me it looks like the "black" is just pigment.

The overall impression I'm getting is that the plant has been sunburned (that's the big dead spot with black ring) and is receiving way too much light, so it's starting to produce dark red pigmentation in the leaves to help protect itself a bit.

I would put it behind a thin curtain or move it back from the window and out of direct light, personally. It's very hard to tell if the plant is over potted, but that pot does look a tad roomy. It's not that you won't be able to make it work, you just need to be cognizant of the fact that the interior may remain wet while the outer portions are bone dry, and that you'll need to adjust your watering accordingly.

I agree with the sunburn diagnosis.
Does it, in any moment during the day, gets direct sun?

Thank you so much for your quick reply! sorry about the low photo quality, I am attaching a better closeup. I feel bad for sunburning it, did not expect that to happen in the rainy Glasgow. I will remove the plant from the window! Please let me know what you think about the blackness, it does not look like rotting to me

I am in Glasgow, it is mostly cloudy. However the past few weeks have been less gloomy and more sunny. I hope the plant would recover if I remove it from my window

The better photo just looks like "suntan". Sudden changes of light can be an issue. (A plant can be introduced slowly to increased light with much less problem) The red color on the leaves is no problem, just says that it was receiving the upper end of the light that it wants. If it is any consolation, I have toasted more orchids in the month of March, when the sun can change abruptly, suddenly clearing the house or surrounding trees, than any other time. So you may also be seeing shift of the sun with the changing season on top of sudden clearing of clouds. Just move it back from the window a bit.

thank you everyone!!

Some Phalaenopsis varieties are naturally red. The redness intensifies with more light exposure. Pretty sure orchids with red flowers / Doritaenopsis hybrids tend to have red tints in the leaves.

That being said, your plant is thirsty! It's easier to burn/redden leaves when a plant is dehydrated. Less light + deeper watering.