Bonsai Nut
Nuttier than your average Nut
It could be caused by roots of the tree infiltrating and breaking the particles down. I screen all my media, so for certain there weren't any fines going into the pot. I was just finding that the surface of the soil would be bone dry and yet the bottom of the pot it was saturated. I'm not sure it would be a problem if I repotted my trees annually, but some bigger trees go several years between repotting.Interesting. I have not noticed turface breaking down. I am thinking what you experienced could be caused by smaller particles sinking to the bottom. But either way, clogging the bottom is not good.