Ohh my wow. Not trying to be off topic but how long have you had that clam for? I'm assuming you bought it close to that size. And I'm think about just getting a HOB refugium as I don't have any room in my actual sump.
I am thinking about setting up clownfish breeding tank (or tanks) and i am wondering where to start and what to use? Should I be drilling glass tanks? Sump? I don't know where to start