6500k, 14,000k, 20,000k

[awestruck]

If I understand correctly, corals grow best under 6500k. This level is unappealing to the eye which is why people go to 14 or 20k. Just curious though, if you are only running MH 20k, how well do your corals grow? Wouldn't 14k bulbs be better?

[awestruck]

anyone?

[Alex T.]

You should do some research on ballast and bulb combinations. There is an excellent link on Manahattan Reefs that Sanjay Joshi put together showing different configurations of ballast/bulb/wattage with some of the most popular combinations of light spectrum.

From what I can tell you, I've run 14k, 10k and 20k. I had the best growth under the 10k bulbs, but colors (even with actinic supplement) started to washout. My 14k bulbs simply appeared very weak and did next to nothing. After checking Sanjay's site you'll notice that the 14k kelvin bulbs aren't necessarily "developed" and there just yet. Par seems to drop off.

After switching to the much touted 20k Radium bulbs with Galaxy electronic ballasts I can tell you that growth is steady and coral color is better. Par isn't everything, and simply choosing bulbs for high par ratings can leave you with a very yellow looking tank...which I personally don't enjoy. My fish also seem happier under the Radiums. They don't sit so low in the rock structure anymore like they used to when the 10k xm's were beating down on them. It's all going to depend on what you want to keep. If you get 6,500 and 10k bulbs you definitely don't need as long a photoperiod sometimes..but again, check Sanjay's site. Here's the link:

http://www.manhattanreefs.com/lighting

[awestruck]

Alex,

Thanks much for your input. Yes, I've been reading quite a bit and definitely will read Sanjay's research.

It's nice to hear what others have found too, because I don't like the yellow look either and your combination sounds very good.

[mfinn]

If I understand correctly, corals grow best under 6500k. This level is unappealing to the eye which is why people go to 14 or 20k. Just curious though, if you are only running MH 20k, how well do your corals grow? Wouldn't 14k bulbs be better?



It is a personal prefference thing. You use the light that you find the most appealling.
For me it's not a race to grow corals, it's about what I like to look at.

I use the Radium 20k bulb in my zoanthid tank and love the color.
However, I do use Hamilton 14k bulbs in my 240 right now. I have used XM 20k's before and liked them also, but switched to the Hamiltons when a good deal came along.

[awestruck]

Thanks mfinn.

I will soon be transferring from my 20g. emergency-set-up to a 65g. breeder 36" L
x 24" tall. Unfortunately I will still have to use my 24" Coralife 1 x 150mh & 2 x 65w. pcs.

When I can afford to upgrade, I'm going through what so many people do: wattage, kelvin, etc. I've thought about 2 x 250w. MH pendants; however, if you use that kind of lighting, do most people use 20k. bulbs so the light is not the ugly yellow? Or, do the colors still wash out because there are no actinics?

[mfinn]

You can get very nice white blue colors from many different 14k bulbs up the 20k bulbs.
Look at the different pictures here on members tanks, look at tanks in your area, stores.
For the first time, I'd pick something in the middle.
If you went for the bulb with the most blue, and then decided it was too blue.........

Look around and do some window shopping.lol

[Toddrtrex]

I have been using 20,000K for about the last 5 years and won't go back to anything else. I like the color and the growth has been great.

Over my 58 I have 2*250 Radiums (( 20,000K )) + 1*96 50/50 PC & 1*96 dual actinic PC.

This frag started like this,

http://i5.photobucket.com/albums/y189/toddrtrex/millieplustopdown.jpg

And about 10 months later,

http://i5.photobucket.com/albums/y189/toddrtrex/Pic6.jpg

[Alex T.]

Todd, that's just sick!

Ten months? Absolutely incredible. Great job.:thumbsup:

[awestruck]

Todd, wow, that's over 10w. per gallon and nothing bleaches?!

[mfinn]

I have been using 20,000K for about the last 5 years and won't go back to anything else. I like the color and the growth has been great.

Over my 58 I have 2*250 Radiums (( 20,000K )) + 1*96 50/50 PC & 1*96 dual actinic PC.



I'm pretty sold on my 250watt Radium 20k over my zoanthids. I use to use
3x55 watt actinic on it but recently switched to 2 x 75 watt VHO 454 bulbs and the difference was huge. The 454 bulbs are great.

[Toddrtrex]

Todd, that's just sick!

Ten months? Absolutely incredible. Great job.:thumbsup:

Thanks a lot. Was a great coral -- lost it when I moved it to one of my other tanks -- it was getting too big.

Todd, wow, that's over 10w. per gallon and nothing bleaches?!

Nope, just as long as I acclimate them to the lights.

I'm pretty sold on my 250watt Radium 20k over my zoanthids. I use to use
3x55 watt actinic on it but recently switched to 2 x 75 watt VHO 454 bulbs and the difference was huge. The 454 bulbs are great.

I would like to do that, but my constant back issues are preventing me from doing anything like that. Not sure why I didn't go with VHO's when I bought the fixture 10 years ago.