Lighting colour temperature

[Frolicsome_Flora]

Ive made an observation that Id like to share with you, and see what you think.

I have 2 different types of tubes over my tank at the moment, Hagen Life-Glo (6500K), and Hagen Aqua-Glo (18,000K).

I did an experiment over 48 hours each to observe how much pearling I could see depending on which combo of tube I was running.

My first setup was 2 Life-Glo tubes, running at the same time, for the same period.
At the end of the photoperiod it was really hard to spot any pearling, except for a bit on my surface Riccia.

The second set-up was 1 Life-Glo, and 1 Aqua-Glo for the same periods.
This time, pearling was considerably more on most of the plants, even the Java ferns.

Hagen do state the Aqua-Glo as a pro-photosynthesis tube, and I guess that all I've done is really confirm that.

My trouble is, is that prolonged use of the Aqua-Glo, spurs my brown algae problem into overdrive, and also I get the horrid signs of early cyanobacteria back again. Ive had an issue with unstable CO2 which is now sorted, hopefully.. so maybe thats the cause of the algae in the first place. Id really like to be able to run the Aqua-Glo full time, at the moment though it just doesnt seem possible.

 

[freshgoby]

This list below describes what Kelvin equals what type of light.
The Kelvin on your bulbs could have given you some clue as to what the results of your test would have been. Imagine running 2 Aqua-Glo's, algae yuck!

Color Temperture in Kelvin
Degrees Kelvin : Light Source
1700-1800K : Match Flame
1850-1930K : Candle Flame
2000-3000K : Sun At Sunrise/Sunset
2500-2900K : Household Tungsten Lamp
3000K : Tungsten Lamp 500-1000W
3200-3500K : Quartz Lamp
3200-7500K : Fluorescent Lamp
3275-K : Tungsten Lamp 2K
3380K : Tungsten Lamp 5K-10K
5000-5400K : Sun Direct Noon
5500-6500K : Daylight (Sun+Sky)
5500-6500K : Sun Through Clouds/Haze
6000-7500K : Sky Overcast
6500K / RGB : Monitor (White Point)
7000-8000K : Outdoor Shade Areas
8000-10000K : Sky Partly Cloudy

 

[VaughnH]

My impression is that many people have no idea what the K or Kelvin rating on a bulb means. They assume that, like watts, the higher the K the better. So, 10,000 or 18,000 seems to be a much "better" number than 5500 or 6700. And, "actinic" sounds like a super dooper version of a bulb. Of course, higher watts aren't necessarily better either, but we still seem to view it as being better. After all the higher the GPH, the higher the gallons or liters, the higher the ppm, etc. the better, so why not watts and K? This sure isn't a hobby for those who don't want to work at learning things!

 

[Frolicsome_Flora]

thanks for all that info Freshhoby

Yeah, ive been trying to learn about Kelvin temps as I think its really important. Do you think that running 2 6500k instead of 6500 + 18000k will yield good growth still?

 

[freshgoby]

Flora - I was thinking that (about trying 2 - 6,500K's) right after I posted. I think that would give good lighting and definitely minimize algae growth. OR you could keep the light the way you have it and start experimenting with your CO2 system and nutrient regimen to match the demands of the lights (though I'd imagine that would be wayyy costly).

I think lighting for tanks should be based more on Kelvin/color temperature rather than wattage. And knowledge of color temperature and how it affects plants is invaluable.

As far as I see it, keeping a planted tank is all about combining and stabilizing the variables (light, CO2, nutrients, water temp, flow, fish load, volume, etc) in such a way that it produces the best results. Define a constant and set the other variables around that. Easier said than done. It just takes time and a lot of research

 

[Frolicsome_Flora]

I find the effect of colour temp really really interesting, Id kinda like to learn the science behind what colours effect the plants and how.. obviously, its definatly the reds that are making the difference. I wonder though that if I had good substrate coverage (its getting there slowly) then things would settle massively and the algae would subside quickly.

I just added 6 Oto's which, after watching them for 24 hours are just amazing fish, the amount they consume is stunning.

The biggest thing I dont want is another cyanobacteria outbreak.. I have signs of it on the bare sand again, after about a week after blackout. But CO2 hasnt been stable in that time.. now I have it stable, Im hoping that the cyano will turn around again and go.. maybe thats wishful thinking. I need to wait it out I think and see how it goes. Its easy to do your own head in by changing things and not waiting long enough to actually see the changes.

 

[Tom Barr]

You can read the Phyto chrome article here on the BR.
It's the only article ever written by a hobbyist for planted tanks on the topic.
I'll be adding to this as I just went through two grad doctoral level core classes on Phytocrome and light photoreceptors. One of the researchers had some nice diagrams that will explain the concepts much better and I can use them to better explain how a plant precieves light and can actually tell the difference between a piece a wood shading it, and another plant just based on the light itself.

Light will upregulate genes in response to the environment in a nut shell. These genes are interelated to many functions and light types, situations etc.
This allows plants to grow, flower and live in many habitats.

Algae also have very similar photochromes and cryptochromes. Thus these are highly conserved genes evolutionarily. Must be of some use likely.

Color temps on the other hand, they are our preception of light, not photosynthesis. When we buy lighting, we buy it general based on the way it looks to our eyes, not on plant growth.
The vendors know this and sell that, because, well, that's marketing for ya


Regards,
Tom Barr