Big, np. Don't worry about leaving 4 bulbs on all day. If you turn off your actinics during the day, it won't look as good and the corals may not like it as much. The actinics are simulating the spectrum of light that reaches the more deepr depths in the wild. Some of your coral may need a full day of it. Here's a pic of my bulbs reflecting on the surface of the water:
The one in front is a Blue Plus. The next one (white) is an ATI aquablue 11,000k. The next one (yellow) is a Geismann 6000k midday. The one in the back is an ATI pure actinic. The outside actinics come on at 9 a.m. and then the middle ones fire up at 10 a.m. They're all on, all day until the middle ones shut off at 8:30 p.m. and the actinics go out at 9 p.m. That's just my lighting schedule. You can come up with whatever suits your lifestyle.
Again, you can click on my little red house to view pics of the tank to see what this bulb configuration will do for you. I took those pics just a few days ago and the bulbs are 8 months old now. They seem to be still going strong, accept the rear actinic may be losing a bit because my GSPs aren't flouresing nearly as much as they were. They normally look very neon green under these bulbs.
If you want the tank more blue, like you said, just switch out the midday one I have for another blue plus. But that will make the tank very blue.
I'm pretty happy with this light setup.
If you want to learn more about them, there's a thread in the Lighting Filtration and Equipment forum called the T-5 Q&A thread. It's VERY long now but you can skim through it and get some ideas.
