These fixtures use 12 3 watt cree xte royal blues, and 12 cree xpe cool whites. They are perfect for nano tanks, and will light an 18" cube no problem. These fixtures can easily support sps, lps, and softies. The Apex dimmable model is $299 shipped, the manually dimming model is $324.99 shipped, the whites and blues are seperately controlled by color-coded knobs.