Hi,
I used to have a tank full of mushrooms. I mean full. Every rock and bit of sand was covered. I put in a finger leather and within a 2 months it start to grow like crazy and mushrooms started to disappear. I only have 1 or 2 now.
Either the leather poisoned the mushrooms, but did not effect any of my other coral, or the leather took what ever nutrients that the mushrooms were using. In either case I was left with lovely finger leather colonies that are easy to trim.
If you try it let me know how it goes. I wonder if my case was a fluke.
-E