[Samper]

Could someone please give me a lesson as to why hardly anyone uses 6500k bulbs anymore???

Also I saw a bunch of pics on Japanese tanks in this thread
http://www.reefcentral.com/forums/sh...hreadid=428375

The use of starboard underneath a tank instead of inside of it has brought out colors on the underside of some of the acros due to the reflection of light. Does this benefit the coral in any way? Doesn't seem natural to me but at the same time am thinking about putting the starboard I ordered under my new tank. It's pretty.

[ricksreef]

except for my 14K halide, all my other tanks have 6500K on'em.
and i still like a sandbed. so i guess i'm not much help to ya...

[Samper]

And you have no qualms with your coloration?
If not I'd rather go with the 6500's since they are the closest thing we have to natural sunlight.

Why are the bigger K bulbs out selling these?

[Reefland]

The problem with them is without very heavy supplementation, they are ugly; simply put. I don't doubt that for growth and some of the brighter coral colors such as yellow and red they are better, but they require lots of actinic.

For the starboard, yes the reflection of light is healthier for the corals since they get more light from varied directions; the problem is it, like a glass bottom, will quickly be covered in coralline algae.

[Samper]

I like the corraline but the Japanese tanks have none in them. If I put the starboard underneath the tank and kept the bottom scraped clean I could have the same affect with minimal effort.

[Reefland]

I wonder how easy it will scrape off the starboard? I would suspect it to have some type of texture that would make it difficult to scrape?

[Samper]

They do have a texture and a few of the guys who use it in tank have reported that life takes hold of it very easily. I know at home the piece I have have nicks and gouges in it from cutting meat and I'm sure that scraping corraline would nick it up. The texture isn't completely smooth either this I'm sure is why some of the Japanese have put it underneath the tank.

[Ninong]

Originally Posted by Samper

If not I'd rather go with the 6500's since they are the closest thing we have to natural sunlight.

Here is something for you to consider:

"Natural sunlight" changes as it penetrates deeper into the ocean. The red end of the spectrum is absorbed rather quickly. The deeper you go, the bluer and weaker the light becomes. You might notice that effect yourself when viewing a relatively deep public aquarium that is lit by natural sunlight: http://www.mbayaq.org/efc/efc_hp/hp_kelp_exhibit.asp

This is why hobbyists who build elaborate, huge reef tanks with gigantic skylights above them to let in natural sunlight, quickly realize that their tanks need A LOT of actinic supplementation to "correct" the appearance.

Some hobbyists prefer to have their reef tank look like "natural sunlight" looks like at a depth of say 15 ft., or 20 ft., or 30 ft., etc. If your aquarium's water column is only 20" tall, then natural sunlight (or daylight lamps) will give it the appearance of sunlight on the reef at a depth of 20" below the surface. Even the 5500-gal reef tank at the Waikiki Aquarium, which is 5' tall, is not tall enough to notice much difference in the sunlight. It is lit by a combination of natural sunlight, 1000w Venture Sunmaster metal halides and 400w Radium 20,000K metal halides.

This is not to suggest that Iwasaki 6500K metal halides are not an excellent choice for a reef aquarium, they are. They just won't make your tank look like a natural reef at a depth of more than 20 ft.; they will make it look like a natural reef at a depth of 20". Again, please don't confuse the efficacy of any particular lamp with the appearance of the tank. The 6500K Iwasaki lamps are EXCELLENT lamps. They have even more blue light than some 10,000K lamps. We can't "see" it because our eyes are more sensitive to the yellow/green range and Iwasaki's 6500K lamps have lots of yellow/green, too.

Without getting into a long, drawn out discussion of the physiology of photosynthesis in corals, let's just say that the appearance of the tank is an important factor in many hobbyists' lighting choices. There are also excellent arguments to be made that bluer light is more natural, and better, for most corals than "daylight" light, unless you are trying to duplicate natural conditions as they are found in the top 20" from the surface.

[Samper]

I have the coralife fixture with 260w of actinics in it. Would you say that it would be visually appealing if I supplemented two 250w 6500's with the actinics? Also what do you think I would notice as far as coloration, polyp extention and growth are concerned?

[Ninong]

Two 250w Iwasaki 6500K metal halides plus four 65w PC actinics would provide plenty of light for a 75-gal tank. I would venture to say that anything more than that would be overkill indeed for that particular tank.

Coral growth and coloration should be excellent. The appearance of the tank is a subjective rather than objective quality. Most people would be satisfied with the appearance. It should appear white. It will not appear bluish-white and hopefully it will not appear yellowish-white, which it might without the actinics.

Again, you may like the look, others may prefer something slightly bluer. I'm running my tank right now with no actinics at all because I had to cut back on my photoperiod for my halides due to heat issues and I wanted to boost total PAR during the period when the halides are off. So I replaced the two 55w PC actinics with 55w Osram daylight lamps. I'm running those 13 hrs/day and my two AB 250w 10,000K HQI DE lamps only six hours per day. I hope to get my chiller installed sometime between now and next spring. But even now we are still having some warm days. Yesterday it was 93F with a heat index of 102F!!!!! Anyway, my point is that even without actinics my tank doesn't really look "bad," it just looks white. With the actinics it looked slightly bluish-white if I used my imagination a lot. Personally I think it needs a 20,000K metal halide lamp in the middle to supplement the two 10,000K lamps. I would prefer that appearance.

[Samper]

You have just made up my mind for me. I've been debating on hanging a 20k DE bulb and pendant in the middle. So here is my final decision on lighting for the 75. I will keep the coralife fixture and have 260w of actinics. I will get two SE 6500 bulbs and one DE 20k for the middle. All will be in pendants and set up on a pully system. Ballasts will be mounted inside the stand. I'm trying to keep this all as "clean" looking as possible so I'll have to work on how I want to hang and hide everything but thank you very much for the tips.

Why are iwasaki bulbs so expensive? I can't seem to find any of the charts that used to be on here but I remember there were bulbs that put out more par and were almost half the price.

[Ninong]

I have always considered Iwasaki 6500K lamps to be very cheap. Both the 250w and 400w sizes are usually available for about $59. I pay a lot more than that for my 250w 10,000K HQI DE lamps.

I'm really not familiar with all the new metal halide lamps from China, Korea and Taiwan that are showing up on the market so I don't know what they sell for or whether they are a bargain or not. I do remember that three or four years ago everybody was going gaga over the Sunburst 14,000K lamps from China until they started "bursting" prematurely.