Iwasaki 6500K - The best reef lighting?

[ChrisRD]

Walt Smith has stated in the past that most of the corals imported for the hobby are collected at depths from 8' to 20'.

Sanjay's latest article in AAOLM demonstrates that a full spectrum daylight lamp like the Iwasaki 6500K more closely approximates the underwater spectrum of sunlight at 5 meters (which roughly correlates with an average collection depth from what Walt has stated) than many other lamps in the hobby would.

If we're really attempting to approximate natural reef conditions in our tanks, based on the information above, it would seem that full spectrum daylight lamps like the 6500K Iwasaki are the most appropriate choice.

Of course with more and more corals being propped/raised in captivity under artifical lighting the point may be moot, but I was wondering what others' thoughts are on this...

 

[MartinE]

I read the same thing many times, the lights are just real yellow, so I guess most folks just use the higher kelvin bulbs for asthetics. Paletta's comparison with the mix of higher kelvin and lower kelvin is probably the better way to have your cake and eat it to=corals are happy with the full spectrum and your happy with the cover up by the 20k or 14k, or acitinics

 

[Anonymous]

Yep. 6500 is the best color temp for growing corals. But they don't color up as nicely as they do under higer temp bulbs.

with 6500's, it looks like someone peed in your tank it's so yellow. (IMO)

Since you've read sanjay's articles, you know that the higher Kelvin rating you go, the less PAR your tank is gettin. The more PAR the corals get, the better for them to grow.

I had a 20KK 150w MH bulb on my tank. Although it was pretty, I saw very little growth, compared to when I had them under 10K PC's! I switched the bulb down to a 14KK (I don't have actinics) and the growth has picked back up. And all my corals look pretty nice too!

B

 

[Tackett]

Yep. 6500 is the best color temp for growing corals. But they don't color up as nicely as they do under higer temp bulbs.

with 6500's, it looks like someone peed in your tank it's so yellow. (IMO)

Since you've read sanjay's articles, you know that the higher Kelvin rating you go, the less PAR your tank is gettin. The more PAR the corals get, the better for them to grow.

I had a 20KK 150w MH bulb on my tank. Although it was pretty, I saw very little growth, compared to when I had them under 10K PC's! I switched the bulb down to a 14KK (I don't have actinics) and the growth has picked back up. And all my corals look pretty nice too!

B

Bingo! bingo. I have also noticed the same trend. I had 6500K PC in a tank and noticed alot better growth, but dang it was ugly.

 

[Ben1]

I ran iwasakis 65K on a eye ballast for years and didnt mind the color either. It was 2 400 watt 65K MH and 4 110 watt VHO actinics over my 75. Best of both worlds....

 

[ChrisRD]

Thanks for the discussion.

I agree with Ben, I don't think Iwasakis look all that bad running on the eye ballasts. Still, I can certainly understand why people might choose more aesthetically pleasing lighting.

As for the Iwasakis not coloring-up corals - on that I'd have to disagree. Some of the most colorful SPS corals I've ever seen were under Iwasaki lamps. Granted, they won't make a drab or brown coral appear more colorful than it really is - something that bluer lighting can sometimes do IME/IMO. Personally, I think there are other large factors at play when it comes to coral pigmentation and that too much importance is placed on lighting in this regard.

On the PAR thing - I think that's exactly what most of us have always assumed was the main benefit of the white/daylight lamps over the bluer lamps - the better PAR. What's interesting though, is now that some SPS keepers have had time to experiment with the new high PAR blue lamps like the Phoenix and AC 14Ks for a year or more, some are reporting that they still had better growth under the 10Ks (despite the similar PAR output of the two lamp types) and are switching back.

That brings up the question of whether or not it's more benefical to our corals to have that PAR coming at them across a wider, more natural spectrum, rather than just concentrated around 450nm (like the Phoenix/AC lamps)...