Colour of light. Important?

**dawugui** · 7th May 2006, 02:09

Guys, saw quite a few lights on Y934.

Just like to enquire, what kind of lights would be better for my 2ft planted community tank? I'm using the fluroscent ones. And how many would be good? Is one enough?

Does colour plays a part in providing light for the plantS? e.g. blue and red? Is it just for appearance sakes? or it does provide the light needed by plants as well as those white fluroscent ones?

**richietay** · 7th May 2006, 11:11

dawugui, actually there is a sticky thread provided by squee on how to start a planted tank. it is quite useful

**|squee|** · 7th May 2006, 12:38

Both PL and FL are fine. The number of tubes you require is based on the type of plants you want to keep.

We only use white light (6500K) for plants.

**dc88** · 7th May 2006, 12:43

Take about lighting color of fluroscent tubes for planted tank, there are a number of controversial view points and data around.

Some references I came across :

- Kasper Horst/Horst E. Kipper (Founders of Dupla) : cool (whiter) color promote bushy growth, warmth (yellower) color promote elongated growth

- Some other German preference (can't remember is it JBL or Denerrele?) - prefer warmth color. It was proposed that DOC in the water absorb more blue light so blue (or whiter light) will break down the Fe-DOC bonding more easily and they may think more Fe = more algae ? (I think the latest school of thought is that it also depend on the plant density and growth rate, so more Fe not necessary = more algae)

- Diana Walstad (Ecology of Planted Aquarium) : she cited an experiemnt done by Richard K. (1987) based on O2 level produced by plant with respect to lighting configuration (2 tubes combination of : cool white, warm white, day light, Vita-light) and the best combination is cool white + vital light, second by cool white + cool white. Her recommendation is to use cool white (for cost reason since the difference between the 1st position and 2nd position is not a lot). She also questioned if the test simply a reflection of light intensity rather than color. (For example, cool white tube tends to have higher lumen than daylight and vital tube). But I think this data does not tell if the plant grow nicely. I think most people would prefer a bushy growth than elongated plant growth, right ?

ADA (Amano) : seem to prefer the whiter extreme very often 7200K light color. As a reference, typical daylight color is around 6500K whereas cool white is around 4800K. The larger number means whiter the color. But cost may be the obsticle to some people to get 7200K tube.

I think there are also experts who went on to measure the absolute light energy (umol/m2/s ?) but normal layperson liked us may not able to understand and apply easily.

I think bottom line is what your vision guide you and what is cheaper in the market. I tried cool white and day light (and its combination) before and finally settle with daylight because of the color to be more natural to me liking. Cool white make the red plant looks really good. But I prefer the daylight color to bring out the natural green color.
I use Osram PL Dalylight 36W, which I bought a box of 10 from the distributor directly, and cost me only $8.5 per piece, and can last me 5 years assuming changing it yearly. I was told Philips Daylight is whiter, but I have yet to track down any distributor of Philips lighting to get some bulk offer.

**dawugui** · 7th May 2006, 16:26

hmmm, thx dc88 for the very detailed explanation.
so you are suggesting i get a whiter version for my planted ones?

**dc88** · 7th May 2006, 22:20

I guess as a start you will not go wrong to use the 6500K daylight that most people use.

Rgds
DC

**dawugui** · 8th May 2006, 06:46

thanks dc man~~
will do so.

**solonavi** · 8th May 2006, 14:36

Typically, plants uses the 400 - 500nm and 650 - 700nm wavelenght.

However, its been widely accepted that plants are able to adjust themselves to the lights condition.

Ya. 6500K is a gd starting point.

Cheers
JC

**dawugui** · 8th May 2006, 17:23

ok~
but on the lights packaging there will state the 6500k right?

**|squee|** · 9th May 2006, 10:25

Yep. Generally the common temperatures we use are 6500K, 8000K, 10000K.

**grey_fox** · 9th May 2006, 12:46

Just to get my misconception, is there any difference between 6,500 & 10,000K T5 tubes? Or rather in what instances would one choose a 10,000K tube when 6,500 is already accepted in planted tanks?

**Justikanz** · 9th May 2006, 14:36

Percieved brightness by the human eyes/brains, I guess. Now that I am used to seeing 10,000K T5 tubes, I find it wierd to use 6500K ones. I will think the tube looks less bright, and even a little yellowish, due to the colour temperature difference.

**grey_fox** · 9th May 2006, 15:08

Yeah which is true, out of the 8 tubes I have, 4 are 6,500K and lows rather dim. I wonder if I use 8 x 10,000K will that be an overkill?

**Justikanz** · 9th May 2006, 15:38

Their lumens should be the same, i.e. their brightness should be the same. It should be a percieved thing brought by the colour. 10,000K might not be too good for plant growth, IMO... But I still prefer the colour...