Why do people run 6500K bulbs?

[Dana Riddle]

@Dana Riddle

What do you believe are the best t5 bulbs for coral, appearance of the tank aside. For example if you had to run a 6 bulb fixture, which would you choose? All one bulb? A mix? I'd be interested to see what you'd put together. It's clear that the iwasaki is a favorite among halides, but what about t5s?

I've only tested a few T5 lamps and that was years ago and I'd have to see if those companies are still around. Those lamps producing light skewed towards the violet end of the spectrum would be my choice, along with a pure actinic, a green one (if its output is less than 550nm) and two daylight lamps. So, 2 -violet, 1 - actinic blue, 1-'pure' green, and 2-daylight. This should cover the full range of the chlorophylls/chlorophyll-peridinin complex and should work well if PPFD (PAR) is at least 100, preferably a little more, in the darkest, unshaded areas in the tank. Using violet and green lamps in lieu of the standard actinic/daylight combo should stimulate photosynthesis quite well since their spectral peaks are outside of the absorption peaks of protective xanthophylls.

 

[Dana Riddle]

Alcohol consumption and internet access are poor bedfellows. You know who you are.

 

[trido]

An interesting debate that reminds me of the old MH arguments and people tearing each other apart over 10k bulbs being too blue and actinic will kill all your corals.

These days we have so many options and there are documented success growing coral under just about everything. Pick a spectrum you like visually and be happy. We can easily add power if you want more PAR or PUR and there are so many things that impact growth more than spectrum (ok, I am talking about normal reefing bulbs - not something silly like 100% green LEDs) heck I have used 6.5k MH, 15kMH, all sorts of T5, PC, blue/white led, blue only LED, full spectrum LED, t5/LED combo - they all grew coral like weeds. If you are having trouble with coral growth it's not the spectrum, add or relocate a pump for flow, increase or decrease intensity, look at the tank chemistry more closely or best yet, spot feed appropriate sized food.

The spectrum seems to play such a minor role in coral growth (again, with normally used reef lights) compared to those other factors I listed that if you like 6.5k then run it! Like heavy blue? Run it! I think the valid point is that the more actinic the more fluorescence but you can wash out other colors with too much blues but whatever someone enjoys.

I do like the point that replicating nature isn't always the most ideal solution, there are so many variables in the ocean that we simply can't replicate in our living rooms and the example of tide pool coral growing slowly due to photoinhibition is a good one. Unless you like the look in which case there is 0 issues! We get caught up in "the best" argument a lot and it typically brings two things to mind.

1) there isn't anywhere nearly enough data out there to make that conclusion for each species and even individual morphs of a species
2) many times what people are arguing about isn't enough to make a significant impact anyway, it's just getting caught up in semantics

This post states it well for me. In the old days the 6500k iwasaki was known for fast growth then 10, 14 and 20k bulbs colored up the corals but slowed growth. As a coral farmer I use whiter light for most of the day to speed growth but keep things blue for higher sales.

 

[Dana Riddle]

This post states it well for me. In the old days the 6500k iwasaki was known for fast growth then 10, 14 and 20k bulbs colored up the corals but slowed growth. As a coral farmer I use whiter light for most of the day to speed growth but keep things blue for higher sales.

Great minds think alike - Using lower Kelvin lamps for growth and higher for color was a recommendation I was making back in 1997 0r 1998. This thread reminds me of even earlier days, when some stated metal halides were a 'poison.' When I published a positive review of PFO's Solaris LED luminaire, I literally got hate mail. The more things change, the more they stay the same...

 

[jda]

I was around in these days - I got my first MH setup out of the back of TFH and you had to assemble it yourself and it came with a 5.5K bulb. How did people state that MH were a poison or that 10K or 14K bulbs are "too blue" and would harm your coral? All that we had were some LFS and a few magazines, and I never remember any magazine articles saying that 10K bulbs were too blue and harmful... the only internet that was around when 10k bulbs came out was 14.4k dial up, a few newsgroups and some BBs.

All of these "people said that MH could not grow coral" or "higher K MH bulbs cannot grow coral" posts just confuse me since I don't remember that at all and I was purchasing and working at a full-time reef/fish store then. I do remember the hype over PCs that turned out to be complete garbage. I remember T5s having the vast majority of good reviews that got even better quickly.

 

[Dana Riddle]

I was around in these days - I got my first MH setup out of the back of TFH and you had to assemble it yourself and it came with a 5.5K bulb. How did people state that MH were a poison or that 10K or 14K bulbs are "too blue" and would harm your coral? All that we had were some LFS and a few magazines, and I never remember any magazine articles saying that 10K bulbs were too blue and harmful... the only internet that was around when 10k bulbs came out was 14.4k dial up, a few newsgroups and some BBs.

All of these "people said that MH could not grow coral" or "higher K MH bulbs cannot grow coral" posts just confuse me since I don't remember that at all and I was purchasing and working at a full-time reef/fish store then. I do remember the hype over PCs that turned out to be complete garbage. I remember T5s having the vast majority of good reviews that got even better quickly.

Without naming names, the metal halide 'poison' comment was made in Freshwater and Marine Aquarium (FAMA) magazine's monthly column on reef aquaria. I'm guessing 1992 or 1993, perhaps later. Of course, many of the corals/false corals kept then didn't require a lot of light and the light intensity produced by halides was probably just too bright, and this statement was representative of our knowledge of photo-adaptation and acclimation capabilities of zooxanthellae clades. But what would this hobby be without controversy? I'm thankful that Reef2Reef discussions are civil, unlike the wild wet days on CompuServe's FishNet, where some of the flame wars got nasty and personal at times.

 

[Midrats]

I was around in these days - I got my first MH setup out of the back of TFH and you had to assemble it yourself and it came with a 5.5K bulb. How did people state that MH were a poison or that 10K or 14K bulbs are "too blue" and would harm your coral? All that we had were some LFS and a few magazines, and I never remember any magazine articles saying that 10K bulbs were too blue and harmful... the only internet that was around when 10k bulbs came out was 14.4k dial up, a few newsgroups and some BBs.

All of these "people said that MH could not grow coral" or "higher K MH bulbs cannot grow coral" posts just confuse me since I don't remember that at all and I was purchasing and working at a full-time reef/fish store then. I do remember the hype over PCs that turned out to be complete garbage. I remember T5s having the vast majority of good reviews that got even better quickly.

Those 5500K footballs grew some coral too. I had a lot of really interesting macros that popped out of the rock, wonder why . I don't knock PCs too much. They were pretty big for 10 years and I saw a lot of really nice reef tanks that used them. I used them on a couple of my most successful reefs in the early Nineties. They're kind of like an old dog to me.

 

[greg 45]

After reading this article I ordered a Iwasaki 65k 400 watt m/h. I just received my par meter that was on loan. I tested one of my 400 w radiums and the par was fair . I removed it and installed a pulsrite 10k . This is over a nem clam tank. 1St day nems not so happy by the 3rd day there size increased from normal to a larger size , clams looking much better getting more light and par. IMO the blue trend is just stopping algae from growing where the 55k is going to grow more algae. Today we over stock our tanks over feed our tanks. Back in the day we didn't overstock with fish , we ran bio ball's . There was more to go wrong back they .

 

[mcarroll]

I can't recall the exact details, but didn't the 6500K's require a special ballast vs "standard" halides?

 

[jda]

I can't recall the exact details, but didn't the 6500K's require a special ballast vs "standard" halides?

There was a HPS version, but also a MH version. The HPS bulbs did indeed run better on a HPS ballast that was more wattage, but would start on a pulse start ballast. I got a hard lesson once on prove vs pulse start when the new 10K bulbs that I bought would not reliably fire on my ballasts until I put ignitors on them.

Greg - that 6.5k bulb might have twice the PAR of a radium, so take some time acclimate. You could see if Dr. Joshi's site has your bulbs and you can get the PPFD for both.

 

[Battlecorals]

Longtime iwasaki user. Many of the corals in the actual pics on my site were grown under iwasaki 65’s on m80 ballasts.


There is no denying they work tremendously well at growing and pulling color out of Sps. They are just visually quite unflattering.


I wouldn’t use them over a display. But they are amazing bulbs to be sure.

 

[Battlecorals]

I can't recall the exact details, but didn't the 6500K's require a special ballast vs "standard" halides?

It was called an EYE ballast. I remember pfo sold them. They were essentially a mercury ballast I believe. but saki’s run on halide ballasts just fine.


It’s funny the last time I bought any bulbs I had to go through iwasaki directly and in bulk lol.

Not many dry good venders carrying them any more.


I’ve got a lot left even in anyone’s looking lol.

 

[mcarroll]

They were essentially a mercury ballast I believe.

That's what I was trying (and failing) to remember! I think they were supposed to be a halide conversion bulb for mercury vapor ballast installations. (Something I know nothing at all about.)

 

[biecacka]

i run an XM10k bulb now and it is quiet the difference from my old radium. Taking awhile to get used to visually for me as most of my colors are brownish to some extent but the color of the tank is coming around and its growing on my. I am seeing it is not as brown as i was first making it out to be in my head.

corey

 

[jda]

Any MH ballast will work for a 5.5 or 6.5 bulb if they have ignitors. If not, then the bulb has to have them.

FYI - that graph that I ran a few pages back was 250W 6.5 Iwasaki on M80 - more than twice the output of a Radium on M80. Amazing stuff.

 

[Big E]

Any MH ballast will work for a 5.5 or 6.5 bulb if they have ignitors. If not, then the bulb has to have them.

FYI - that graph that I ran a few pages back was 250W 6.5 Iwasaki on M80 - more than twice the output of a Radium on M80. Amazing stuff.

The 400w Radium with the PFO HQI was/is the perfect compromise...........you could get good growth and the eye pleasing pop in corals and that crisp white/blue ambient look..............add those VHO actinics and it was sweet.

The biggest game changer to me for acros were the Lumenarc III reflectors. Once you got all that light over the tank with all those facets it made a huge difference in coverage. Of course those type of reflectors are common now as many companies copied that design. This led to people moving to 250w bulbs as the extra wattage wasn't needed to get similar results.

 

[BradB]

You are missing the historical context. 6500K halides were around before reef tanks, higher kelvin bulbs generally were not. So 20 years ago, you could buy a cheap yellowish bulb at the local hardware store that lasted forever, or order an expensive bluish bulb at your LFS or mail order you were supposed to change every 6 months. At first, the aquarium community opinion was the ordinary bulbs wouldn't grow coral, or not as well. But people started using them on frag tanks and grow out tanks anyways. Then the aquarium community's opinion seemed to shift to 6500K is the best spectrum for growth, but the bluer the bulb, the better the color of the coral. People now realize you can get great growth and color under anything 6500K or very blue, or anything in between, so it mostly person preference. Personally, I love the look of coral under very blue lighting, but avoid it because I am mostly fish centered.

 

[jda]

Ed - they are even more impressive down to 350nm and up 825 or 850. These spectrums are still very important as Dana illustrated a few pages back. I still think that if somebody started to build 400W HQI ballasts again that they would still sell quite well today. I went to 250s on M80 because I could run two for almost (close) the same wattage and have better coverage... plus the PFO ballasts are hard to find and I only have 4 of the 400W HQI versions and I would need probably 4 more.

 

[biecacka]

I am thinking of switching to 2 250 watt bulbs instead of a single 400 for the same reason JDA mentioned. Better spread, marginally more electric.

Corey

 

[Bpb]

I’m a big fan of the 6500k t5ho bulbs. I use

4 blue+
2 True actinic
2 6500k.

It is probably whiter than a lot of newer reefers would prefer, but the blue and actinic darken the look up quite a bit and tame the 6500k. Having been out on the water a handful of times it looks to me similar to what my eyes see at about 15-20 feet deep.

Really wish I had access to a par meter to see what kind of neighborhood I’m in.

I’ve never used the famous iwasaki 6500k bulbs. But I have used Radiums, xm10k, all manner of t5ho, and pure LEDs. I’ve always had the most stable growth from t5ho. I did have the most explosive growth from xm10k and I loved the look of them, but my bulbs frequently wouldn’t fire and would shut off randomly, despite trying several batches, and using brand new m80 ballasts. So I bailed on them because I value reliability above all.

To be honest, I’ve befallen tank tragedy after tank tragedy and have never gotten to observe a tank grow out from frags to big colonies, so performance difference between various color bulbs on t5ho has been negligible to me. I tend to just shoot for what I like the best looks-wise. Mostly from the overall ambience of the room. A blue dominant tank tends to make the room look too cold.