Just a few questions about t5 lighting.

[MUCHO REEF]

Depends on how long you run them. I run two blue bulbs in the am and pm for a few extra hours each day, so I replace the blue bulbs every ten months. I have noticed a pronounced detioration near the end of the bulb life, and don't like replacing them all at once, so I start replacing bulbs at ten months (blue morning and evening bulbs) and then one a week until they are all replaced by the eleventh month. I tried going for a whole year on bulbs and the last month didn't do my corals any favors.
I agree that ATI are the best bang for your buck in the bulb department.
I don't believe you can run HO bulbs in a RO fixture.
I have used an equal number of ATI Blue special and Blue Plus bulbs and been satisfied with growth and appearance. I believed that a "whiter" bulb was necessary for good coral growth. Based on what I have read, I am no longer convinced of that. I believe the PAR values to be the primary consideration, and the appearance of the tank is a matter of personal preference. I am starting an experiment with three Blue Plus and one Blue Special bulb over my frag tank. If I don't like the results I will swap out one of the bulbs for another Blue special. I currently run four Blue Plus and two Blue Specials over my display tank. Not too white, not too blue, good growth.

+1, awesome answer MyNemesis. Bulb lenght is always based on usage time. I also agree, and you make an excellent point, not to change all of your bulbs at one time. Staggering the replacements is great advice. Bulbs which have greatly diminished in their effectiveness that are all changed at once could cause polyp retraction and possible bleaching.

2 thumbs up.

Mucho Reef