Originally Posted by Bartman
Ok I'm understanding a bit more but the first three are T5?! not PC. I think I need to do alittle more research on these lights
haha its cool man. What follows is purely based on the Watt/gallon rule. The first 3 are indeed T5, but they are four 39W bulbs... that's 156W total, but only 3.9 W/gal for your tank. #4 and #5 are 192W total, giving you 4.8 W/gal, but they are PC. Any of these fixtures will be fine more most softies probably, but not for clams and more demanding corals.
One other thing to keep in mind (which relates to your question about arrangement of bulbs to put in the fixtures), is that bluer lights aren't as good for growth as whiter or yellower lights. But, they look much better
. You've probably seen the color temperature of the bulbs, for example 10000K for the "daylight" bulbs. The higher that number, the bluer the color is, and the lower the number, the yellower. 10000K is pretty much white. Actinic lights are something different, I'm not sure how much, if any, benefit they give to coral growth. I believe they are used for looks (because they make the tank look really cool!). So, keep that in mind when you consider how you'll arrange the bulbs (I don't have any suggestions, unfortunately... someone else will though I'm sure). If you used a two-bulb fixture, with one daylight and one actinic, then you're getting even less "useful" light since half of the wattage is in actinics.
If you have a tank with a bunch of 6700K bulbs, you'd probably get good growth, but the tank would look ugly lol. If you go with 14000K or 20000K bulbs, the tank would look pretty cool (bluish tint), but growth would be slow. I don't even know if T5 or PC bulbs come in color temperatures higher than 10000K, but metal halides do. The typical arrangement of T5 and PC fixtures is some 10000K and some actinics, half-and-half. Maybe with a 6-bulb fixture, you'd use 4 daylights and 2 actinics?