K rating on bulbs and Plants.

[PlantedFishGeek]

Ok i hope gets me a solid answer without sparking a massive debate. What Kelvin rating on the bulbs should i be running, i have looked at bulbs on a number of sites and they have 3000k,4000k,4100k,5000k,5500k,6000k,6500k, 6700k,8700k,9000k, 10,000k, 12,000k,14,000 I have even seen 20,000k bulbs but those were MH. There are also 50/50 bulbs,Actinic, Fiji Purple bulbs, and the Weird pink "Plant Grow Bulbs" All this is a bit much for the Average Joe to sort through and figure out.

Here is some info the "website" lists not sure on accuracy,6500K for rooting and vegetative growth stages.3000K for flowering and fruiting growth stages.4100K spectrum for rooting and vegetative growth stages.5000K for rooting and vegetative growth stages. It is just confusing, does this mean i need one of each of these bulbs?? Or will a 6500k bulb do everything that a 3000k,4100k,and 5000k bulb will do?

I have a 10,000k bulb right now.

Is there an "Ideal" K rating for a planted tank,if so what is it?

Are 10,000k bulbs good for planted tanks?

So What K rating is best Avoided in a planted tank?

If it should be a mixture What K ratings are Best?

Please Answer the above assumeing CO2,Ferts, Etc AND for a low tech no Co2,no fert tank.

Thanks in advance!

[Carissa]

Anything from 4000K - 10000K is fine. Pick what you like the looks of.

[PlantedFishGeek]

Anything from 4000K - 10000K is fine. Pick what you like the looks of.

None are more effective than others? A balance isnt needed? I have often wondered if maybe my 10,000 wasnt part of why i have problems with plants, because the mosses i have in my smaller tanks under a 6500k bulb look far better!

[VaughnH]

I would say between 5-10.000K is a good rule of thumb. That number is not a real color temperature anyway. Fluorescent bulbs emit light depending on what phosphers are coated on the inside of the bulb, with each one contributing one spectrum line. The "best" bulbs have 3 phosphors, so they have a more even spectrum than those having 2 phosphors. If you have plants and or fish that have red, and you want to see the red, you need a bulb with some red in the spectrum. The highest numbers usually are the bluest white light, sometimes lacking in red color, but not always. The GE 9325K bulb isn't blue white at all - it is a red violet color, which is jolting the first time you see it, but then your eyes adjust and you notice how beautiful the reds in the plants and fish look. I have read that the 8800K bulbs do a similar thing.

So, it comes down to what looks best to you. Actinic is generally beleived to produce light too far out of the spectrum of light that plants need, so they are useless for a planted tank. And, they have a single phosphor, as I understand it.

[ceg4048]

So, it comes down to what looks best to you. Actinic is generally beleived to produce light too far out of the spectrum of light that plants need, so they are useless for a planted tank. And, they have a single phosphor, as I understand it.

Hi Hoppy,
I agree with the first sentence but not the second. Plants uses any light energy in the visible spectrum. Therefore if you can see the light then plants can use it. Actinic peaks in the 420 nm range which is blue. This is at the lower region of the visible spectrum but still quite useful. If the entire tank were filled with actinic light then the plant would fabricate auxiliary pigments in order to convert this wavelength to other useful wavelengths. Having said this though a tank completely lit by actinic would look very dim to our eyes since human vision is optimized around the green wavelengths, however they can have a very nice effect when used in combination with other bulb colors - with no disadvantage whatsoever. In fact, blue is the highest energy visible light since it has a shorter wavelength and higher frequency. I don't have a PAR meter to confirm but it wouldn't surprise me at all if an actinic bulb delivers a higher photon flux compared to a red bulb of equivalent power rating.

Get any bulb that looks nice, without regard to K values and your plant will use it. In any case, as hoppy points out, the K ratings of bulbs are almost strictly propaganda as they seldom adhere to the black body radiation Kelvin scale.

Cheers,

[Carissa]

This is interesting to me. I've wondered if it really makes a difference if you have a wider spectrum of light or not. Actinic bulbs are very narrow in spectrum, which is the only reason I can see that it wouldn't be useful light. I've read that blue light actually has the most penetrative power in water (as evidenced by the fact that in very deep water, everything looks blue), also I thought that actinic bulbs were created to simulate the spectrum you will get in deep water. But in our relatively shallow tanks, I'm not sure if having extra blue light would really matter much as far as having extra penetration power. Also, you can buy "full spectrum" plant bulbs. Are these just a hoax more or less?

[beastboi]

From my understand 6500k is the best for plants, 10,000k does nothing for the plants at all.

[Carissa]

This can't be true....I have 10000K bulbs on my tank and my plants grow just fine.

[aaronnorth]

From my understand 6500k is the best for plants, 10,000k does nothing for the plants at all.

the reason most people reccomend 6500k is because it isnt too blue or red, it shows off the green colours of plants and it is 'supposed' to be similar to the suns colours which in turn is 'supposed' to make the plants grow better

But it doesnt!

If you go with 2 tubes, i would go with a 6500k & a 4000k, this way it will show off the all natural colours of plants, a great combo IMO.

[Gilles]

Well you are all wrong, in a way. Not that i am the expert but it all comes down not to what colour temperature the light is (e.g. that is only for us to see) but what spectrum the bulb emits. There are those who emit more red, those who emit more blue, just like ceg4048 is telling.

On my tank, i have Philips TLD T5 HO 830, 840 and 865. Which means; 3000K, 4000K and 6500K (e.g. natural sunlight).

Other than that, there is the lumen question. How many Lumen does a specific bulb emit (lumen versus Watts). There is a dutch article ( Licht in het aquarium ) which explains it all very detailed and also mentions the lux that certain plants require to grow optimal. I have no enligsh translation but maybe there is a dutch to english translator?