Mike,
Goni's are a very funny thing, and unfortunatly I don't mean that in a good way. Some people have good luck with them but most don't. they are considered to be one of the hardest coral to keep.
The reason being is that not alot is known about them. Even guys like Bob Fenner are still asking alot of questions, and not getting any answers. Some say they die a slow death due to starvation, looking good for awhile then looking worse and worse. I learned this the hard way when I got one a few months ago. Ever since I put it in the tank it has not been fully extended. On a good note though, my piece is a branching one, and one of the branchs appeared to die. Over the last month or so I see new growth on the dead branch. And the other 3 branchs are extending more. Maybe I'll be lucky and this one will be happy.
Heres how mine is placed etc. On the sand bed propped up with a rock, (some articles I've read said don't place on the rock as they don't do well) in very lite water movement. I target feed all my corals 2 or 3 times a week with a mix of formula 1, cyclopezz, and rotifer put in the blender, once small enough add in dt's phytoplankton. Don't blend again. Turn off the tank and feed with a turkey baster. Leave the tank off for 15 min to 1/2 hour. This gives time for the stuff to stay suspended in the water for a while. The goni has a better chance of filtering food. IMO.
Hope this helps, PM me and let me now how it does. Maybe if yours does well, I can learn something to help mine more.
Robin