# 12000k and 18000k for Plants?



## thatgmc (Jul 4, 2010)

Just bought a new Current 24" fixture for my planted tank. The guy gave me 18k Power Glo and a 12k Sun Wave bulb for it. From my understanding, these are not optimum color temps for growing plants. Should I swap them out for 6500k?


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## thatgmc (Jul 4, 2010)

BTW, I have HC, tropica, downoi, fissidens, rotala, and narrow leaf java


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## chad320 (Mar 7, 2010)

6500K, ive seen 8800K, or 10K will do. It really depends what your eye likes.


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## jgmbosnia1 (Oct 18, 2010)

12k and 18k are no good for growing plants. From what I have read they are great for growing algae!


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## snausage (Mar 8, 2010)

jgmbosnia1 said:


> 12k and 18k are no good for growing plants. From what I have read they are great for growing algae!


Very true. Especially in a tank supplemented with fertilizers. Maybe leave one of the 12K bulbs up front for aesthetics and swap the rest out for 6500K and lower K bulbs.


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## OverStocked (May 26, 2007)

jgmbosnia1 said:


> 12k and 18k are no good for growing plants. From what I have read they are great for growing algae!


Nonsense.


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## 150EH (Dec 6, 2004)

I have studing this lately and it seems to be that 5k to 6500 is best for a planted tank, bulbs in that range are very hard to find. 6700 is the most popular and I have found 5500 bulb that is compared to morning sun. I did have a 50/50 split of 10k and 6700 and everything seemed fine but I always did have a bit of algae on the slow growers and hard to clean places in the tank. I think above 10k is out of the spectrum of light required for a planted tank but to be honest I have never tried anything that high on the kelvin scale.


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## Darkblade48 (Jan 4, 2008)

The colour temperatures on the Hagen bulbs have always seemed suspicious to me; how can you have an 18 000K bulb that is not extremely blue?


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## thatgmc (Jul 4, 2010)

Thanks guys. I will go ahead and switch over. It's just weird that the fish store guy would recommend me those bulbs. I thought maybe there was some new breakthrough on what spectrum was ideal for plants.


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## 150EH (Dec 6, 2004)

I think they would have been great for a marine tank and in my experience even stores that sell plant sometimes know nothing about the setup.


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## xmas_one (Feb 5, 2010)

thatgmc said:


> Thanks guys. I will go ahead and switch over. It's just weird that the fish store guy would recommend me those bulbs. I thought maybe there was some new breakthrough on what spectrum was ideal for plants.


"fish store guy" 

9 times outta 10 they know zero about what they are talking about..


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## jgmbosnia1 (Oct 18, 2010)

OverStocked said:


> Nonsense.


I think it would be nice to at least say why you think it would be nonsense. I was simply stating what I have read on the matter. If you have something of value to add then please do. I am more than willing to learn something new. Just saying NONSENSE doesn't help anyone in this case.


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## ktownhero (Mar 21, 2011)

jgmbosnia1 said:


> I think it would be nice to at least say why you think it would be nonsense. I was simply stating what I have read on the matter. If you have something of value to add then please do. I am more than willing to learn something new. Just saying NONSENSE doesn't help anyone in this case.


I think he's saying it's... nonsense. What evidence is there that higher k bulbs promote algae? The burden of proof is on the person asserting that claim. It doesn't make sense to me that a bulb that doesn't help plants helps algae. I've never seen a properly cared for and lit reef with blue bulbs have major algae problems. 

Sent via Android


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## Neya (Nov 21, 2009)

Theres evidence too much red light promotes algae growth. I personally have never seen anything that too much blue promotes algae. Reef tanks would be covered in algae, I mean some are.. but usually that has other reasons behind it (bad husbandry, old bulbs that have shifted in spectrum etc)

12k-18k may wash out some colors you like (reds?). Also, plants utilize quite a bit of blue spectrum, so it may actually be beneficial? 
You could use the 12k and 18k bulbs, if they look good to you. If not, sell them on a reef forum and grab some 6.5k-8k bulbs.


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## yajur (Mar 4, 2011)

iam useing 12k lights only but i not seeing any algae issue


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## fresh.salty (Jul 2, 2010)

That 18k bulb didn't look good to me at all. Might be ok in a 4 tube setup but with just two bulbs it was hard to cover up that look.


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## OverStocked (May 26, 2007)

ktownhero said:


> I think he's saying it's... nonsense. What evidence is there that higher k bulbs promote algae? The burden of proof is on the person asserting that claim. It doesn't make sense to me that a bulb that doesn't help plants helps algae. I've never seen a properly cared for and lit reef with blue bulbs have major algae problems.
> 
> Sent via Android


This is exactly what I'm saying. Why do I need to disprove something when there is not evidence against me? 

TOO much light, not enough co2, and not enough ferts is the cause of algae. Kelvin ratings are what WE see. They ahve little to do with the actual output of the bulb.


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## jhunt (May 7, 2010)

I use an 18000 k bulb on one of my tanks for color balance without any problems. I also used a 12000k bulb for a while with similar results. The k color has little to with plant growth. Most of the better bulbs come with a spectrum analysis that will tell you how well a bulb will really work. The k color is what we see, the spectrum analysis is what your plants can use.


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## snausage (Mar 8, 2010)

10000k and above bulbs simply aren't good for growing aquarium plants or any terrestrial plants. I'm not saying it's purely because of the kelvin rating; they suck because their spectral output readings are always poorly distributed amongst the critical areas of the spectrum for virtually *ALL* types of plant growth. 

Go to a reputable online hydroponic store and see if they carry any 10000K or above bulbs (they won't). Amongst their huge selections of bulb types (t5ho, mh, hps, cfl etc) all of them will have kelvin ratings from approximately 2700k-6500k.


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