I'm having a lot of trouble with a Calanthe argenteostriata. No matter how I treat it (low water, keeping damp, light seaweed based fertilizer, no fertilizer, shade house culture in Spain, now windowsill culture in the Netherlands) the leaves just keep blackening from the tips downwards, and now the new growth from the edges inwards. Other (evergreen outdoor) calanthes and (windowsill) phaius are not having those problems. Despite the size of the new growth and visible pseudobulbs in the somewhat blurry pic I just took, the root mass occupies about 70% of the pot. Any other growers successfully dealt with similar problems? Thanks!