Hi
from personal experience suns tend to do well if you feed them cyclopeeze
there will definetly open up if you target feed them daily around same time
as for current and light of course it will be better if its under low light and stong
current (correct me if wrong)
however from own experience do not think it matter much as long you target
feed them
As for dying suns you will find the stem or base losing color
hope this helps and would welcome any comments as am still newbie