Matt,

With no actinics I would suggest you take a look at the spectrum of the bulbs as well as the PPFD. Color is nice, but the corals will never develop good color without a good 420 nm peak. I have been having problems with my VHO actinic ballast and I just got it up and running a few weeks ago. The corals are really starting to color up from the added actinic. Its amazing. That's another thing I don't like, besides the PPFD, about 20K. The spectrums I have seen on the 20K have almost no 420 nm. Its almost all in the 450-460 nm range.

I am using XM 10K now. I chose them for their broad spectrum as well as 420 nm production. What I did not know at the time was that they also have some consistency problems. One of the bulbs I got last fall was pretty yellow when I first put it on, but this has seemed to reduce since it has burned in. That may have more to do with my eye becoming accustomed to the color then the actual spectral output.