i just added to my 29g tank a couple of feather dusters, nice rock with lavender mushrooms, a long polyp leather and a tiny kenya tree. this tank has metal halides. i put all of the new stuff on the sand bed for now. how long do i need to keep them low in the tank before they are ok out in the open? right now, i have the top glass covered with an opaque piece of cloth to filter the light.