14 or 10k MH?

[Jolieve]

So this is my question of the moment. After the holidays I need to replace my 250w DE bulbs on my tank. I currently have 10,000k AB bulbs in there. I'm really liking the look of them, but I'm wondering if my corals and clam will fare better long term under 14,000k bulbs.

Any thoughts on this?

J.

 

[Anonymous]

I don't believe there's a big difference with respect to your livestock...I'd pick the one most aesthetically pleasing.

 

[Unarce]

Not only would the 14K be more aesthetically pleasing, but would probably be more healthy for your corals.

 

[Anonymous]

So there is a difference?? Huh.

 

[Unarce]

Yeah, it's not a very popular point of view, since most would lean towards the supposed growth advantage of lower kelvin ratings.

Still, the strongest photosynthetic activity in corals are when they are exposed to the bluer spectrum, which incidently, is what they are exposed to most in the wild.

 

[SnowManSnow]

I like 20k myself especially if you dont have supplimental actinic lighting

 

[Jolieve]

I don't have actinics, but I don't like the look of 20k bulbs. The tank is in my Victorian decorated formal living room... I know it's wierd and random, but somehow it really goes with me. I don't want to throw the whole thing off by going purple.

J.

 

[SnowManSnow]

Just for the sake of comparison here is a picture I took for another post recently. The paper is held directly under my 20kMH pendant.. I erased a true white square in the left corner for comparision. Not too purple for me... but we all have our opinions

B

 

[Anonymous]

If you like the look of the 10k stick with it. Corals like bright light, that's really all you need to know. Even 10k is bluer than sunlight.

IME, the higher K bulbs are not as bright.

 

[Ben1]

10k may be bluer then sunlight but what after the sunlight is filtered through some ocean water?

I just added a geisseman DE 14.5 K 250 watt to my 20 gallon long, it blows my old 175 out of the water. In anycase the bulb isnt burned in yet but it looks nice to me. I am getting very close to the same color I was getting when running 10k plus actinic PC sup. Just much much brighter...

 

[SnowManSnow]

Would the light from a higher k bulb actually be less bright? Or is that just what we see with our eyes. I guess a luxometer would tell the tale. Neither here nor there, but a good question

 

[Anonymous]

10k may be bluer then sunlight but what after the sunlight is filtered through some ocean water?

Sure. Most of our corals are adapted to shallow waters however, and most do fine at 6500 or 10K wavelengths. If anybody has proved otherwise I haven't seen it.

My brightness comment is just on my own experience; my 10K de 250 bulbs are about a kajillion times brighter than my 400w mogul radiums. There are many other variables in play though, so I wouldn't stake much on that.

 

[RSanders]

..."10k may be bluer then sunlight but what after the sunlight is filtered through some ocean water?"

Ocean water isn't blue. The blueness only come from the reflection of the atmosphere.

~R

 

[Unarce]

I just added a geisseman DE 14.5 K 250 watt

Ben, so the Geisseman does have a blue tint to it? I'll be changing bulbs after the new year and I'm torn between the Megachrome 14.5K DE 250 and the Aqua Connect 14K DE 250. I was leaning towards the latter after hearing the Megachrome was more white than blue.

Would the light from a higher k bulb actually be less bright?

I definitely would say the lower K bulbs are brighter, which is indicated by their PAR level. Still, brighter isn't really better:

http://www.science.uts.edu.au/des/Staff ... hesis.html

Sure. Most of our corals are adapted to shallow waters however, and most do fine at 6500 or 10K wavelengths. If anybody has proved otherwise I haven't seen it.

The corals will do their best to adapt to what aquarists put them under. One reason that some may not like the color of their corals under lower K lighting (aside from the yellow tint), is because it can encourage darker zooxanthellae strains that effect the pigment which protects the coral from UV and the unnecessary wavelengths that intense lower K light are dominant in.

http://www.reefs.org/library/talklog/s_ ... 02/pas.jpg

In cases of established coral farmers and distributors that collect from the wild, they find it imperative to keep wild colonies under 20K lighting.

Ocean water isn't blue. The blueness only come from the reflection of the atmosphere.

It's not that the water turns blue, but what is actually filtered through. At high noon on a clear day, you'd expect a Kelvin rating of 6000K at the waters surface. The Kelvin rating increases considerably after every meter. After only 3 feet, the longer red, orange, yellow, green wavelengths are absorbed quickly and reduced to roughly 50 percent, with the efficient, short blue wavelengths becoming dominant. After several meters (where most of our corals originated), the longer wavelengths are almost non-existent. The light filtering by the water for proper coral spectrum cannot be duplicated in our aquariums.

 

[Ben1]

Ben, so the Geisseman does have a blue tint to it?

It's bluer then my 10k ushios I use, both 175 and 250 SE. It still seems very white though. Its so bright though my 55 watt PC actinic does nothing for the color. If you wait a few day, I will post a picture of my tank with the 10k Ushio and one with the 14.5k geisseman. The AC is probably is the better choice.

 

[Unarce]

Thanks, Ben!

I'm still on the fence between the two, so pictures of your Megachrome would help a lot. I might also opt for the 20K Megachrome.

 

[Anonymous]

In cases of established coral farmers and distributors that collect from the wild, they find it imperative to keep wild colonies under 20K lighting.

Have any evidence of that?

 

[Unarce]

Sure, Dan. Most of what I discovered came from private correspondence whenever I try to pick the brain of those that run these facilities, but here's a couple of reputable sources that list it on their website:

http://www.drmaccorals.com/sys-tmpl/scrapbook/

http://www.reefermadness.us/RM-NewsRoom.htm