Dendro's in the sump
 

I've been struggling keeping a little frag of sun coral's going for a while. when i first got my new job and was home every day i got them coming out every night when i had not seen them since i got them. then they just kind of blah'ed out again.

would they do better in the LRR portion of my sump? there is lots and lots of pods down there perhaps they could get some natural feeding?
or do they need a lighted portion of the day to know when to open and close?

I feed mine silersides once a week, they seem to come out quite frequently. It kind of defeats the purpose of having the dendro if you cant view it in the display. btw dendro and suncoral feeds on different types of food. I feed my suncoral mysis and acan plus. I also keep them in a shaded area of my tank. They don't seem to like bright lights.

Try shutting off all the powerheads and pump and than target feed the sun coral with Acan Plus or another food with syringe. When it senses the food near it, it should open up and feed.
You need to do this at least once a day.

The sump is not an option.

Why not get a dendro instead of a sun coral? My dendros are always out, always.