The meaning of Lights?

[MizTanks]

Evil, I don't know how to thank you (((((hugs))))) how's that, lol. I have learned much from you today. I now feel that I am capable of choosing the correct lighting for what I would like to grow in my tank, and what I shouldn't try without the proper lighting.
Of course I will read this many times. Just another reason for me being here at CR. One thing I have learned, that I've never really delved into until now. Is knowing about the corals I wish to keep, their requirements when it pertains to light and how important it is to research them all.

Thank you again for this wonderful explanation of LIGHTS!

Jamie.

[MizTanks]

I'm truly trying to understand what would be the best light source in a lamp that I could run for the betterment of my corals that depend on photosynthesis as their food source.

There is a shop here that is totally dedicated to lights for growing indoor plants. I've stopped in with my corals in mind. They deal only in MH and LEDS, sadly I could afford neither.

What do MH and LEDS offer that other light sources don't? Is it their high par, high kelvins?
What does *watts* have to do with coral growth is anything? i.e. 150~250~18~24, ect ect.

Thanks again Evil

Jamie

[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]

What do MH and LEDS offer that other light sources don't?

It's all to do with spectral output and relative intensity. Each light source creates light in a slightly different way. Some light sources can create light more efficiently in some wavelengths better than others. That doesn't mean that any one light source is worse than others. It just means that some lights are more efficient. As long as the lights can provide the corals what they need at the right intensity, then anything can be used. PC's have typically been considered the bottom rung of the lighting ladder, but that's only because manufacturers have been always considered them a cheap, and less critical technology. As a result, the phosphors used have been sub-standard compared to T5, even though they are basically identicle. Companies like Current USA, UVL and Hamilton have been using T5 phosphors in their lamps for a while now, and the difference in output over your standard PCs is considerable. Now, PCs will never be as powerful as T5HO because of the geometry and reflector issues.

Is it their high par, high kelvins?

High PAR only does you good if the light is in the right wavelengths for what you are growing. Obviously, most lights targeted for reef lighting are set up the right way, so more PAR is better. But, there is a trade off with color. If you like deep blue tanks, then you don't always get the option of having super high PAR. For the most part, as long as you don't venture outside of what is considered the norm for reef lighting, it all works.

What does *watts* have to do with coral growth is anything? i.e. 150~250~18~24, ect ect.

Thanks again Evil

Jamie

Watts has very little to do with anything. It used to be a simple metric to use back in the day when PCs were still very popular to guage the relative performance of the fixture over a certain tank. It was the old watts per gallon rule. This all gets back to efficiency. T5HO, MH, and LED all produce more light per watt, so putting the same wattage of light over the same tank now means you are putting more light into the same area. LEDs were really the technology that put the last nail in the coffin for that old rule, as LEDs can produce tons of PAR for very little energy used.

[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.

[MizTanks]

Hi Evilc66

Haha gotta another question for you. I just have to pray you understand this one because I'm not even sure how to ask it right.
When it comes to photosynthesis and the corals that totally rely on it, what are we looking for in our lamps to recreate this process? I think you may have touched on this in previous posts but I haven't quit got it yet is it a combination of pars and kelvins?

[evilc66]

This is the photosythetic action spectra



This is basically shows how effective different wavelengths are at feeding the photosynthetic process. This graph combines chlorophyll A and B. You can find the graphs for each chloropyll online easy enough if you want to break it down further, but this shows what 99% of reefers want to see.

If you want the most ideal light source, recreate this. It's not very practical, and it's not going to look good either. It would be the most efficient use of energy though. The important area that we want to hit is the area between 420nm and 460nm. That's where the bulk of the work is done. The area between 630nm and 680nm is important too, but not quite to the degree that this graph shows. Those are the two peak areas of the visible spectrum where photsynthesis makes the most efficient use of the light.

[CalmSeasQuest]

Thanks for the chart Clive - The 650-680 spike does seem to argue for the inclusion of a "bit" of red, either through red LED or a few warmer whites?