In my tank I have somewhat of a ledge that I tied riccia to pieces of slate and laid them all out to grow. A couple of months later I had a most excellent lawn of riccia. Then I read that riccia should only grow to about 1/2" or it starts to rot on the bottom, so I decide to give it a trim. Sure enough, some of it is turning brown where it's tied down. I trimmed quite a bit of it and it's still taller than 1/2", but it looks horrible. Totally horrible. I'm thinking I need to learn a bit about trimming riccia.