# Acceptable colour temperatures for compact fluorescent?



## jeff63851 (Feb 23, 2005)

Hi all,

I was wondering what an acceptable colour temperature range for compact fluorescent lamps. I used to use 10,000K CFs but they are very costly to replace.

I’ve looked into a few places that sell compact fluorescent bulbs for general use, but I’m not sure if the colour temp is acceptable for aquatic plants. There are some bulbs I’m looking at with 3,000K, 4000K, and 5000K range.

Would it be ok if I used two 5000K bulbs and two 3000K bulbs? Is there a huge difference between 4000K and 5000K?

Thanks!


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## Seattle_Aquarist (Mar 7, 2008)

Hi jeff63851,

Typically I use bulbs in the 5000K to 10000K range. I like 6700K best for plant growth but 8800K - 10000K has more of the blue spectrum. 5000K makes my tank look more yellow than I like. Here is a source I have read is reliable and I am looking at trying next time for my bulbs.


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## niko (Jan 28, 2004)

Anything above 3500 is good.

Do not assume that comparing Kelving numbers means much. Different manufacturers label their bulbs differently. There is a wide variety in the appearance of bulb X a bulb Y and both claim 10000K.

Best bet - get Giesemann Midday 6000K T5HO. If you can't fit it over your tank or you don't have money/time to get a T5HO setup then get any Compact Fluorescent. They will be fine, plants will grow fine under them. And you should think of trashing them soon because they are an obsolete technology and there are much better bulbs out there.

--Nikolay


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## rich815 (Jun 27, 2007)

Look around online and you should find ones that are not so costly. The ones you see for general use in a hardware store and such are cheap and will grow plants but I think you will be disappointed by how dull yellow they make your tank look. I personally like a 6700/10000 combo by using one of each. Check online for AH Supply and Hello Lights.


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## ddavila06 (Jan 31, 2009)

i think it depends on wheter you like it or not with a more yellow or blue color. i personally don't like the yellow-look as much, i have one 65k and 2 10k T5HO on both my tanks...now i don't know whats more beneficial to the plants, ha! i let that be answered by the experts


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## Newt (Apr 1, 2004)

I always get a kick out of people choosing bulbs by the kelvin temp. Seems in the USA most people prefer 6700 to 10,000K with a few people even trying SW actinic (salt water tank keeper wannabees).
In contrast, the europeans choose lower around 4100 and up to 6000K.

In the summer months I like to use a combo or Sylvania GroLux Std and GroLux WS as dawn/dusk lighting. The WS is 3400K and the Standard is probably up around 18,000 to 22,000K. Makes a nice low light warm glow.


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## Newt (Apr 1, 2004)

niko said:


> Anything above 3500 is good.
> 
> Do not assume that comparing Kelving numbers means much. Different manufacturers label their bulbs differently. There is a wide variety in the appearance of bulb X a bulb Y and both claim 10000K.
> 
> ...


Absolutley correct about kelvin bulb ratings. As if the 9325 is really 9325K. LOL

Personally I couldnt stand the yellowish/blue white color and poor CRI of the Midday. They did make my plants pearl nicely.

Do you really think the CF/PC bulb will disappear soon?


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## MrBlackThumb (Aug 30, 2005)

Man, CF is going away soon? I have 2 tanks with CF lighting from ahsupply. I suspect only the ballast can be used for T5? Or am I wrong? Reflectors, bulbs, end caps, bulbholders have to be changed for sure. Near obsolete as it is, CF grows plants pretty well.


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## Newt (Apr 1, 2004)

MrBlackThumb said:


> Man, CF is going away soon? I have 2 tanks with CF lighting from ahsupply. I suspect only the ballast can be used for T5? Or am I wrong? Reflectors, bulbs, end caps, bulbholders have to be changed for sure. Near obsolete as it is, CF grows plants pretty well.


Personally I dont think CFs are going anywhere soon. I think Niko meant they were 'old hat' (i.e. obsolete) bulbs for lighting and to move onto T5HO. Now LEDs are making a move but I think it will be awhile before they can prove themselves. I've yet to see a spectral output graph for any of them and w/o that they are worth a damn IMO.

A ballast like a Fulham Workhorse 5 can run (2) 55w biax bulbs (CFs) or (2) 40w T12s or (3) 32w T8s or (2) 54w T5HO. T8 and T12 bulbs use the same lamp connectors, just wired different.


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