10k 20k?
- Thread starter CREEPIN
- Start date
tippMANn98
Has been struck by the ban stick
10k is more on the white side, and 20k has a bluer tinge to it...
tippMANn98
Has been struck by the ban stick
the only difference is the spectrum, and what it will look like to you...usually you combine a 10 k with an actinic 420/460 nm to make the "normal" look, All depends on what you plan on keeping. coral wise
Octoman
Well-Known Member
Just posted this on another thread...
Lighting the Reef Tank: A Primer for Beginners by Doug Wojtczak - Reefkeeping.com
"When it comes to metal halide color spectrum, there is no one general rule of thumb, but some general observations can be made. Many hobbyists use metal halide bulbs with a Kelvin rating of 6500, and these bulbs produce a warm yellow/white appearance that simulates the midday sun on a shallow reef. Bulbs of this color are well suited for high light demanding corals and clams. While hobbyists report great success using these bulbs, they often complain of their yellow appearance when used without supplemental actinic light. Another common bulb is the 10000-Kelvin bulb, which produces a white appearance with a slight hint of blue. Although many hobbyists have also had good results using these bulbs over most types of corals, some have noticed that coral growth rates are somewhat slower than those using 6500-Kelvin bulbs. Gaining much wider acceptance and use lately is the 20000-Kelvin bulb, often called a Radium, which has a blue colored appearance. These bulbs are better suited for deeper water soft corals and LPS, although many hobbyists have also had success using them over clams and SPS."
Lighting the Reef Tank: A Primer for Beginners by Doug Wojtczak - Reefkeeping.com
"When it comes to metal halide color spectrum, there is no one general rule of thumb, but some general observations can be made. Many hobbyists use metal halide bulbs with a Kelvin rating of 6500, and these bulbs produce a warm yellow/white appearance that simulates the midday sun on a shallow reef. Bulbs of this color are well suited for high light demanding corals and clams. While hobbyists report great success using these bulbs, they often complain of their yellow appearance when used without supplemental actinic light. Another common bulb is the 10000-Kelvin bulb, which produces a white appearance with a slight hint of blue. Although many hobbyists have also had good results using these bulbs over most types of corals, some have noticed that coral growth rates are somewhat slower than those using 6500-Kelvin bulbs. Gaining much wider acceptance and use lately is the 20000-Kelvin bulb, often called a Radium, which has a blue colored appearance. These bulbs are better suited for deeper water soft corals and LPS, although many hobbyists have also had success using them over clams and SPS."
tippMANn98
Has been struck by the ban stick
u said what I couldnt fit into words....i wasnt sure on the 20k for deep water, i was gonna put that...but you eased my mind...thanks for that info Octoman
kathywithbirds
Well-Known Member
I'm kinda gettin' into the SPS a little and they seem OK with my two 150w 14K halides but I also run the actinics all day too. The actinics come on earlier and off later. It's not a spectacular actinic bulb, coralife I think. So far so good. Can't say they're growing fast though. Bulbs are my next project so I'm following lighting threads.
kathywithbirds
Well-Known Member
I'd like to do that! But alas, finances and space prohibit massive bulb purchases 
A lot of it depends on what the reefer want. If your eyes like blue go with a higher kelvin bulb. Some par and intensity may be lost though and coral growth will be slightly sacrificed. Personally, I have run 10-15k bulbs with actinic supplementation. With no actinics, I would probably go with 20k's. Seems like the trend keeps going bluer.
NATIVEVAMAN
Member
I have spent the last year and a half reading just about everything I can get my hands on with a strong emphis on lighting and here is some of what I have learned.The color temp of sunlight at the equator is 5745K.That is truly full pectrum light.From that point on all the way to 20000k the light becomes continually bluer.More than a few studies have been done to indicate that the best coral growth occurs near 6500k.This is logical because coral have evolved over millions of years growing under a 5745k light.The major problem with 6500k light is that it makes a tank look awful.Now 20000k light makes the tank look great almost everyone loves them.However the same articles say that 20000k light promotes the worst coral growth and generates the lowest par of any bulb on the market.20000k is so far from the natural enviornmental light that corals thrive in that it is logical that 20000k light would not promote very good growth.A happy medium of 10000 or 12000k with actinic supplimentation seems to be the answer.Most agree that at 14000k the bulbs are blue enough to stand alone (without actinic suplimentation).
mps9506
Well-Known Member
You also have to take into consideration what depth the corals grow in as well. The deeper the water the more the spectrum will shift towards a 20k light as the reds, yellows, greens get filtered out by the water first with blues and purple wavelengths reaching deeper.
Many reefers that have been in the hobby for a while (not even that long ago) will remember pretty much every ran 6500k Iwasaki's and Hamiltons as that was almost all that you could get your hands on for a decent price. Imported Ushio 10k's were very expensive compared to Saki's (like twice the price).
If you really want to emulate a shallow water reef, then 6500k would hit the sweet spot, but 10k would definately promote more coloration in your corals and also allow your eyes to see the color better as the coral hues aren't washed out by all the excess light in the red and yellow wavelengths.
Currently it seems the hobby has found a nice swet spot for general reef lighting in the 10-14k range that gives a good balance of growth and colouration.
If you would like to read a bit more about light quantity and intensity versus light spectral quality read here:
Aquarium Frontiers On-Line: Feature
Many reefers that have been in the hobby for a while (not even that long ago) will remember pretty much every ran 6500k Iwasaki's and Hamiltons as that was almost all that you could get your hands on for a decent price. Imported Ushio 10k's were very expensive compared to Saki's (like twice the price).
If you really want to emulate a shallow water reef, then 6500k would hit the sweet spot, but 10k would definately promote more coloration in your corals and also allow your eyes to see the color better as the coral hues aren't washed out by all the excess light in the red and yellow wavelengths.
Currently it seems the hobby has found a nice swet spot for general reef lighting in the 10-14k range that gives a good balance of growth and colouration.
If you would like to read a bit more about light quantity and intensity versus light spectral quality read here:
Aquarium Frontiers On-Line: Feature
heels92
Member
Hijacking this thread a little. Here is the question. Does the actinic lighting have any value to the actual coral growth/health if I am running a 250w 14k MH, or does the actinic just help with the visual effect of the coral?
I have had an algae bloom here recently and have not been running my actinics for the last couple of days at all. I plan on starting them back up once I get the algae under control (not that it is that bad.)
Again, bottom line, do the actinic bulbs have any value to corals if you are running MH?
Thanks for any input.
Darrell
I have had an algae bloom here recently and have not been running my actinics for the last couple of days at all. I plan on starting them back up once I get the algae under control (not that it is that bad.)
Again, bottom line, do the actinic bulbs have any value to corals if you are running MH?
Thanks for any input.
Darrell