Usually, the reason for brown corals is both excess nutrients and less than ideal water parameters. Lighting is rarely the reason for coral coloration, longterm. When I say that, I mean the coral may not be the color portrayed, but certain lights may make them look better (or Photoshop may do it as well).
Grue asked: Marc, you chose to use 250,400,250 in your MH setup. May I ask why you chose those intensitys? Will that setup give more light than 150,150,150 and that is the reason you chose 250,400,250? If so Why not 400,400,400 or 250,250,250?
The reason I have a 400w bulb in the center of my tank is because I'm using a 20,000K bulb. That bulb has less PAR than a 10,000K bulb.
By mixing various wattages as I have done, the PAR is more even across the tank. PAR is all about lighting intensity.
Grue asked: Let's say there are only 10000K bulbs available. With that in mind, The different intensities would be because of water depth? Let's say 150w for 20" & 250w for 24+?
I would keep it at 250w per bulb with 10,000K, and use VHO Super Actinics to get the blue I wanted.
Which I've done in the past.
Grue asked: I have 2x96w Actinic (t-5) and 2 150w MH So I am a bit under lighting. When It is time to do a bulb change I will replace them with 250's and new ballasts.
If you plan to upgrade lighting, you might just bite the bullet and get nicer reflectors at the same time. You'll get far more intensity, more space to work in the tank since they hang higher, and less heat added to the water.
If you use SE bulbs instead of DE bulbs, I think you'll find you can save money per bulb. I've been running my lights in these reflectors for two months now, and each bulb is on a total of 6 hours per day, staggered over a 9 hour period. Remember to acclimate your livestock to new lighting -- you cannot just swap them out and leave the timers as they were. The intensity will be double or triple what it was, and corals will not be able to tolerate it. This was explained on this page along with a bunch of numbers to consider:
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