The meaning of Lights?

[tankdude]

Thanks for all the great information on lighting evilc66.

[evilc66]

Believe me, there's a lot more. I'd be happy to answer more questions on the subject, but we need to keep the subject fairly well focused. I don't want to see questions like "what T5 bulb combo should I use?"

[iyachtuxivm]

Great info always nice to see someone willing to help out!

[evilc66]

tankdude, where in Shelby are you? We've probably tripped over each other in Kee's. Heading there after work as a matter of fact.

[Heidi]

I wonder about light a lot too. I hope this question is direct enough here goes:
I have a MH 250 pendent it came with a 20,000K lamp.
1.Do any coral need more then this lamp? Is there any color of light I should be adding to this for my corals health? (I am not terribly concerned with the way everything looks just yet, I really want to just grow my coral).
2. My lamp came w/ the fixture so I figure it's elcheapo. How do you know when you need to replace your MH lamp, do they burnout like a normal light bulb, dim, or is it just a timed thing like after 12 months you replace it?

Thanks again for your help!
-Heidi

[ShanaS]

i have the same question as Heidi, when do u need to change a bulb, when it burns out? or sooner, will you know for sure when your lights are bad? or just go by the 8-12 months and change em?

[evilc66]

I wonder about light a lot too. I hope this question is direct enough here goes:
I have a MH 250 pendent it came with a 20,000K lamp.
1.Do any coral need more then this lamp? Is there any color of light I should be adding to this for my corals health? (I am not terribly concerned with the way everything looks just yet, I really want to just grow my coral).
2. My lamp came w/ the fixture so I figure it's elcheapo. How do you know when you need to replace your MH lamp, do they burnout like a normal light bulb, dim, or is it just a timed thing like after 12 months you replace it?

Thanks again for your help!
-Heidi

1. No, not really. The only difference between a lamp like you have and a different brand/color temperature is the amount of PAR it produces, the color of the light, and the average lifespan of the bulb. Typically, cheap bulbs will perform poorly in all three categories. Quality name brand bulbs will always perform better. Now, not all bulbs of the same color temperature perform the same, so some research may be needed to find the best balance. Typically, the Phoenix 14K is a no-brainer, with deep blue coloring (more like 20K), good fluorescence, and long life.

2. Like I mentioned before, cheap bulbs have shorter lifespans. So what does that mean? Well, it doesn't mean that the bulb will burn out after 12 months of use. Typically, there is a spectral shift (changes color), and a drop in intensity. The higher quality the bulb, the longer it will take for that change in performance to happen, and the relative drop in performance will be smaller. The spectral shift can be problematic, depending on how bad it shifts. The major spectral spikes could shift off, and become less effective for coral growth, or could induce unwanted issues like increased algae growth. Most of the time, the worst issue is a loss in intensity. The 12 month cycle for MH is to reduce the shock to the tank once the bulb is replaced. The longer you let it go (and you can let it go quite a while with certain bulbs), the more careful you have to be with acclimation. I've been running a 150W Phoenix 14K for a little over a year with little to no ill effect, but had another Phoenix start creating algae issues at 18 months.