metal hallide

[TBRUZZ]

I just recently replace(last sunday) took my 250 mh and replaced them with 400 dual ballast hqi..any recommended what bulbs to use? currently running 20k radim(2) over the lps,leather, rose bta:side and on the sps side ushio 20k (2). tank dimensions are 98x24x21. I also have 65k aswasaki(sp.?)...I read somewhere that sps grow faster with them...Do they keep there color or turn brown?? or does it enhance there color? I just can't handle the yellow tint.. With the 400w would you sill use vho's? I haven't use mine since sunday.(660 icecap ballast with 4 super r acinitic).

What brand of bulbs are recommended??

[Spanky]

Dunno TB, I use 10K's.

bump^

[tankgirl2]

I've heard great things about the 20K radiums. I'd still use the actinics on a longer cycle. They bring out the cool fluorescenct color and I believe they're very good for corals. Don't forget to acclimate the corals to the higher Kelvin and wattage mhs.

[tdwyatt]

prop tank for stoneys and other light needy autotrophs: 6.5kK iwasakis, even the 400 watts, as they whiten up with age. Personally 400 watt apps are overkill for most shallow prop systems, 250 is plenty.

display tank, at 24 inches deep, you might consider going back to the 250 and use DE ushio 10kK bulbs, as the 400 watts may induce some bleaching in stonys near the surface. Might depend on what your keeping and how deep you make the reeftop from the surface (but clams will do well on the bottom in that tank...

[tankgirl2]

oops- something I figured out for myself was here.

[ruhspolostar]

What are the best Mh, I want to upgrade

[tankgirl2]

Do you mean brand or Kelvin or wattage?
Also, it depends on your particular corals and tank dimensions. Then there's best for growth, color, best visual appearance, etc.?

If you keep mainly sps, and they're all within ~ 18" from the water surface, then imo, the answer is; Iwasaki's or the XM 10k's
But Tom likes the Ushios (as mentioned above) and it's all heavily debatable.

Some posts to underscore the need to acclimate;
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JB_NY post:
I found a really good way to acclimate to new lighting is turn off the MH after 4 hours then after an hour turn it back on. Doing the on/off 4 on 1 off was recomended by eric bournman once and it seems to work very well for me.
I thought the same thing on quickly bleaching a coral. Eric explained that corals take time to ramp up to fully using the light. It takes place over a 4-hour period. So if after 4 hours you shut down the light, not enough time has passed for the coral to expel any of its zoox. Anyway I've had great success with that method, so thought I would throw it out.
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Doug Lowey post:
I had some severe bleaching when I switched from 400w Iwasaki,s to 400w Radiums, but only pulse start driven. That to me shows how much a different spectrum comes into play, as the Iwaski,s were still new and perhaps 30% more intense than the Radiums.
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And a nice site with pictures and a technical analysis of bulbs;
http://www.coralreefecosystems.com/l...ut%20Analysis:

[tankgirl2]

p.s.
Here's a great thread that shows some test results for various bulbs;
http://reefcentral.com/forums/showth...5&pagenumber=1

PAR (Photosythetically-Active Radiation) is what matters to your corals. As you can see from the thread the Iwasakis (6500Ks) and XM10Ks had the best PAR rating of all the bulbs.

[tdwyatt]

Originally posted by tankgirl2
PAR (Photosythetically-Active Radiation) is what matters to your corals. As you can see from the thread the Iwasakis (6500Ks) and XM10Ks had the best PAR rating of all the bulbs.

Sanjay's lighting article on MH bulbs

Please note the values for the DE ushio bulbs (double ended hqi bulbs) in the 250 watt range...

[tankgirl2]

Tom, that was interesting, however, did you notice the higher PPFD for the Ushios was all in the violet or red spectrum (not blue & green)? I'm not all that expert on lighting, but that seems odd. Also, the Ushios had twice the UV output (a little scary).

Can't believe they tested so many Coralife bulbs.

[tdwyatt]

This is true for these bulbs. All the HQI bulbs require UV shielding (a simple thin glass pane) to filter out UV, as they do not have the outer protective envelope that mogul bulbs possess. It is mandatory that these bulbs have the shield between the bulb and the specimens, and that ample shielding be provided for tank viewers as well, as the UV from these bulbs (in fact from ALL MH bulbs) can be damaging to the cornea and the lense of the eye, intreasing the potential for cataracts in these optical organs.

Good case for totally enclosed lighting hoods.

Sanjay had the opportunity to get a batch of Coralife bulbs for free, unfortunately they did not test out quite so well as predicted.

[tdwyatt]

Also, keep in mind that this is the wavelength that penetrates water the best. Few corals depend on red wavelength light, most all depend significantly on yellow down to UV depending on depth.

[Reefdude5]

What's the difference between mogul bulbs and non mogul?

[tankgirl2]

Austin, I think (for reef purposes) the choices are either mogul or double-ended (DE). Mogul is just a single-ended bulb.

Tom, I was reading that Harker article on natural reef lighting and he mentioned that violet light is also attenuated with depth (along with the red end)? Here's the quote and link;
http://www.animalnetwork.com/fish2/a.../2/default.asp

As one approaches 30 meters or 100 feet, the only light that remains is between 450 nm and 550 nm (Dustin 1982). Note that both blue and green remain and that both shorter and longer wavelength light is attenuated.

[tdwyatt]

Yup, everything turns blue as you go further down, to the point that even the blue filters out. As you dive down, torch light becomes the only means to tell what the "real" color of items are on a dive. Autotrophic corals are limited to the photosphere, some are limited by the actual color of light, some by intensity. Other partial or non-autotrophs and some related organisms are limited to the areas outside the photosphere, either by growing in caves and overhangs when near the surface, or due to special pigments to capture very dim light and UV at or past the edge of the photosphere.

Although UV was once thought to be filtered out at shallow depths, the current data (as measured by meter) demonstrates UV down to 50m and below in clear sediment-free seawater. Normal attenuation in sediment-free low planktonic seawater is as follows:

• at 5 m red and orange have been filtered out
• at 10m, yellow is filtered out
• at 16m, green is filtered out, leaving the blue and UV light
• at 50m most visible spectrum is filtered out

Light in the 480nm range has the greatest penetration in seawater of all the wavelengths in visible light. As energy in the particles goes up, the ability to penetrate water goes up proportionally (all the way to x-rays and cosmic particles). Spectral fields in open oceanic waters near coral reefs at 50m is in the 440-490 NM range, depending on water clarity and substrate coloration.

Most of the attenuation of all wavelength light occurs within the first 3m of the water column, with over 50% of the light being attenuated at depths of 1 to 5M depending on conditions. Deep-water coral spp. typically require less than 20% of the light available at the surface, often blue to violet in color and nature, and may account for the coloration of these corals (as their zooxanthellae are often less a part of their coloration than the photopigments present in the coral, and the accessory pigments are not the brown we expect in healthy phototrophs). Most of the shallow water spp. (in 3m or less), require 50% to 60% of available surface radiation. This is further affected by the colonial position and morphology of the individual corals, with vertical columnar specimens receiving less than 25% of the same light available to horizontally oriented colonies at the same depth.

Corals in the open ocean are common down to the level where PAR has been attenuated down to 1%, and is almost always in the blue-UV spectrum. I can't remember the name of the particular group of accessory pigments, but there are some spp. of corals (can't remember this either right now) that use these special pigments to capture energy in the UV spectrum for photosynthesis and to amplify the available visible light to drive photosynthesis at these depths.

I might point out that those corals that exist in the shadow of other corals depend on reflected light to gain the necessary light energy to drive photosynthesis. For those of you that go BB, you will need to add some surface to the bottom of the tank to reflect light (as the infamous Spankster Starlight Substrate, or SSS does). This not only provides light for these understudies, but also provides light for the underside of the surface colonies as well. Sunlight is closest to the 6000-6500 K spectrum, and this would seemingly be the best color for reef lighting, but the changes that occur to the lighting as it passes through air and water may affect how well we duplicate color and intensity of photosynthetically active radiation for corals, and even the rendition for viewers of such systems. I am not sure that we can pick one particular bulb that is best for all the reasons we choose bulbs, as these bluer bulbs seem to drive both better color variation (the "blue beasts" like Acropora Tortuosa and related color morphs) while better overall growth seems to depend on both good K rating and PAR (i.e., 6.5kK and good PAR near 100).

Not sure that there is a good answer to the overall question, it seems like the playing field on the subject changes as we study it, but that is just my opinion...