IceCap is just known for making some of the most efficient ballasts available -- not necessarily the best (many show strengths), but definitely one of the best. I've got the IceCap Reef Illuminations fixture, 2x250w halide, 2x54w T5, 2x30w LED... and I adore the thing. The biggest key, IMO, is that you'll want to get a digital ballast. Magnetic ballasts just don't carry the efficiency of a good digital ballast, regardless of manufacturer..

-Justin