# 5000K or 10000K?



## cradleoffilthfan (Jan 19, 2009)

Also, the fixture in question would be a 30" with 3, 24" bulbs staggered across the 8" wide fixture.


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## kamikazi (Sep 3, 2010)

I'd do 5000Ks or see if you can mix and do 2-5000K and 1-10000K


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## Wasserpest (Jun 12, 2003)

10000K can make light green plants like glosso look a bit sick/pale/white. So for those it might be good to mix in some lower K bulbs.


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## cradleoffilthfan (Jan 19, 2009)

When he asked me I just told him to go with all 5000K, but I have been reading that if you have an 18" deep tank(plants are roughly only 15" from the light with substrate taken into account) you need the higher PAR readings of the 10,000K bulbs and the 5000K bulbs will give you less PAR.......I just want to make sure I have the sufficient lighting for the Glosso.....I was even thinking of having him maybe put two 10,000K bulbs on the outsides of the fixture and the third bulb in the middle be a 5000K, but maybe two 5000K bulbs on the outside and the middle bulb be 10000K would be better? I just want it to work....


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## JasonG75 (Mar 1, 2011)

I like 6500K


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## Wasserpest (Jun 12, 2003)

Color temperature and PAR are NOT related! The color temp is just a number, it can not represent the spectrum of a bulb. You could have a 5000K bulb with most of it's spectrum in the yellow-green range which would give you a pretty low PAR. Or one that is 5000K (get it?) with spikes just in the right red and blue ranges, with a very high PAR.

That said, unless you have a PAR meter, don't worry about it. Mix some bulbs, and go with what looks best to YOU.


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## Soujirou (Jun 16, 2008)

I used 5500K 36" CF bulbs from AH Supply for years and that particular type of bulb seemed to encourage vertical growth rather than horizontal growth. It was most noticeable with my water sprite where a single plant would send out multiple stems with most leaves near the surface.

Recently, I switched to a 36"-48" Marineland Double Bright, which appears to give a cool white look with more blue/less yellow than my previous bulb. I don't know if my water sprite will send out multiple stems again, but I can say that the new leaves are probably twice as broad as the older ones.

So my guess is that you should only use a 5000K bulb for looks.


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## Steve001 (Feb 26, 2011)

cradleoffilthfan said:


> I have a fixture being made by Catalina, he asked me if I wanted 5000K bulbs for plants or 10,000K.....I didn't really know, I have never used a 5000K bulb before. I think all my bulbs for freshwater have always come with 6,700K. I do remember using 10,000K bulbs before in a compact fluorescent fixture, but that was because I was using a reef fixture over a freshwater tank and just leaving the actinic bulb off. The results were good, but I remember the lights were really white. What should I choose? I am getting these new lights because I am trying to get my Glosso to spread across instead of growing vertical......I need all the light I can get. Am I going to lose too much par because of the 5000K bulbs? He mentioned they are a plant grow type bulb(the 5000K)......choices choices.


Ask them why they don't offer a 5500K bulb.


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## zonamav (Feb 27, 2004)

As a heads up 5000k bulbs are really yellow. Imo they are pretty ugly actually but thats just me maybe. Makes the water look yellowed and stale. 

It's amazing how much whiter and cleaner the 6700k looks. So I would pick the 10k for looks alone.

Sent from my VM670 using Tapatalk


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## hbosman (Oct 5, 2006)

I would just ask for the 6500 K bulbs. Catalina's 6500 Ks are nice color, not as yellow as lot of bulbs in that K range. Their 5000 K *plant bulbs* might be pink so, I wouldn't ask for all the bulbs to be that. You could mix the plant bulbs with the 6500 Ks as well.


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## hbosman (Oct 5, 2006)

By the way, Catalina's 10000 K bulbs look more green than blue....to me anyway. When I got my fixture, I ordered 2 6500 Ks and 1 10000 K but, didn't like the 10000 K so I put my Giesmann 6000 K in its place.


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## kamikazi (Sep 3, 2010)

Soujirou said:


> I used 5500K 36" CF bulbs from AH Supply for years and that particular type of bulb seemed to encourage vertical growth rather than horizontal growth. It was most noticeable with my water sprite where a single plant would send out multiple stems with most leaves near the surface.
> 
> Recently, I switched to a 36"-48" Marineland Double Bright, which appears to give a cool white look with more blue/less yellow than my previous bulb. I don't know if my water sprite will send out multiple stems again, but I can say that the new leaves are probably twice as broad as the older ones.
> 
> So my guess is that you should only use a 5000K bulb for looks.


A bit off topic but I wanted to address the verticle/horizontal growth. The key to getting horizontal growth in my experience is trimming. All plants will have a tendency to grow towards light. However, some plants will stay shorter in higher light, but higher light doesn't necessarily encourage horizontal growth. And since the K range doesn't have to do with how much PAR the bulb produces, perhaps what is going on in your case is the double bright has more PAR, maybe better reflectors as well; thus there is higher light in the tank than before, which might help keep your plants shorter, but they are still going to grow up towards your light unless you trim.

Water sprite is an excellent example of a plant that if left alone will just grow tall and out of control. If you trim it you can keep it more compact and bushy.


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## cradleoffilthfan (Jan 19, 2009)

Just e mailed Catalina. I asked him to put two 10000K and one 5000K bulb in the fixture, but kinda hinted that I wanted 6,500K to 6,700K bulbs. It was odd to me that he said all he had were either 5,000K or 10,000K bulbs though..........I figured he would have had something in the 6,700K range if he was making a lot of fixtures for planted aquaria.......


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## chirping_blue_bird (May 5, 2012)

Please buy a 6500K with CRI 90-95 for a planted tank.

Plants grow well in the full spectrum which falls between 5000K - 7500K..
If you want your plants to grow well and green without algae problems. 6500K is the key.

10000K + are for marine tanks.. Thats the spectrum that coral/reef need


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## Wasserpest (Jun 12, 2003)

This reminds me... take everything you read on these forums with a grain of salt. Just because something is stated in some convincing tone, it doesn't necessarily have to be correct. :icon_mrgr

Again... Color Temperature and plant growth are not related. There are some 2800K bulbs and some 18000K bulbs which are both excellent plant grow bulbs. It is the spectrum that matters, and even that isn't that crucial. Plants are very adaptable as long as there is a certain intensity that allows them to photosynthesize.


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## vincenz (Jan 29, 2012)

Wasserpest said:


> Again... Color Temperature and plant growth are not related. There are some 2800K bulbs and some 18000K bulbs which are both excellent plant grow bulbs. It is the spectrum that matters, and even that isn't that crucial. Plants are very adaptable as long as there is a certain intensity that allows them to photosynthesize.


That's true, but most people don't want to look at red, purple, or blue lights too.


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## cradleoffilthfan (Jan 19, 2009)

I talked to a couple people with these bulbs, I guess they are getting good growth from them and are a midday type of bulb, but just give off a slightly more pinkish hue. We will see how it goes and if it looks like crap, I will just have to buy a 6,700K bulb to even out the aesthetics. I will post pictures here when I get the fixture.


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## bradlgt21 (Mar 24, 2010)

Did you get the fixture setup and get pictures done? I am in this position too. I am thinking of doing there single T5HO to be a medium light option in my 55 gallon. But with only 1 bulb I know my options are limited so the bulb has to be perfect. I want good plant growth but want a bulb that brings out the red and oranges in my fish. I have sunset rainbows which are a dark orange almost red, and these are the main theme of the tank, a bulb that washes them out will ruin the tank. I was leaning towards the 5000k or the 6500 they have on there website but neither say anything about reds and oranges. Only the 3000k and I can't even imagine using that as my only bulb.


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## Hoppy (Dec 24, 2005)

Rainbow fish colors are produced by an interference effect in the scales of the fish, not by pigments, so it isn't necessary to have the same color light to see those colors. Maybe I'm not saying that correctly, but it is certainly true that Rainbow fish colors are not from pigments, like other fish colors are.


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