Adding lights to a reef aquarium canopy really puts the finishing touches on your setup. However, you may find out that you need more of them to get the look you are after.
When we added the canopy to our aquarium and mounted the lights inside, it raised them roughly 8 inches higher than we had them. This caused the lighting in the aquarium to be noticeably darker. To remedy this, we purchased two more T5 lights, which not only makes the aquarium brighter, it allows us to have the adequate lighting for certain types of corals we have been wanting to purchase.
The two T5 bulbs we added were from the same company as the previous bulbs we bought, ATI, but we chose to add a Purple Plus bulb, as well as another Blue Plus.
The Purple Plus bulb brings out more of the pinks, purples, and red colors in an aquarium. The Blue Plus bulb has a shorter wavelength than white lighting, so it can penetrate deeper into the tank, can help to blend out the yellowish green tint that comes from white lighting, and overall looks best (in my opinion) in an aquarium.
So in total, we have two Blue Plus bulbs, an Aquablue Special (white bulb), and one Purple Plus bulb. Arrangement of lights is solely based on preference, and varies from aquarists to aquarists. Most people prefer a blue look in their tank, as do we, so we placed the blue bulb in front. Behind it, we placed the white bulb, then another blue bulb, and lastly the purple bulb.
We have the blue bulbs wired to the same ballast, and the pink and white to another. Some aquarists turn their blue lights on in the morning, before their white lights, and leave them on later, after the white lights have turned off, to simulate dawn and dusk. This creates a more natural lighting cycle for the aquarium. We have not chose to do this as of yet, but may consider it in the future when we get more fish. I have read that some fish only spawn during dusk or dawn, so replicating this time and lighting in the tank is important if you want your fish to breed or deposit eggs.
Below you can see the difference in the lighting. Pictures never do a tank justice, in comparison to seeing it in person, but you should be able to tell the lighting difference: