holes

Hello fellow saltines, This is actually for a stand holding my freshwater tank but I figure the knowledge might come in handy for a future stand for my saltwater tank. The stand is fairly well made but it's lacking shelves in the cabinet area. Totally makes sense for a large canister filter but...

My hammers were huge and splitting. After introducing some new hammers 2 of 3 heads died on my green hammer and now my orange is receding and dying. As I was performing an Iodine dip, I noticed holes in the coral - see picture. Does anyone see the problem from the picture? I was told the little...