Bill,
It maybe that your make up water isn't the same salinity/pH/temp as your tank water. (Btw, I like to age my nsw for a few days if not a week or more. That way I can really sock the oxygen to it.) Flow is also a consideration. It could be the lack of a skimmer, it could be anything?
I know that for the first 6 months, that I couldn't keep any coral alive. I don't know why, that's just the way it was. It may well be the case for you. I know that's no comfort to you, but just give it time.
Now, I can not for the life of me grow soft corals. They just don't like me. So I switched to lps, which do much better for me. I've also gotten into zoa's which are doing somewhat well in my system. It drives me crazy not being able to have what I want in my tank/s. Maybe your system will be better off as a softy tank.
Anyway, aren't you going into a larger tank? Things will be easier with a larger volume of water, less flucuations in the daily params. And none of the constrates that those darned nanocube have.