Tried already with a piece of a match...it seems to be welded. So, I didn't insist...
In the meanwhile I will buy a pot maybe a litle bit bigger and new medium. Which one do you recommend?
I got for my phals a bag of medium suitable for epiphytes, medium size bark, and small spheres made of what seems to be pumice. It's very airy and provides good drainage. My phals like it.