Solar lighting

[Nemos Janitor]

Kelvins (from the Kelvin temperature scale) that we use to talk about light regards the colour of the light.

It is derived by using Kelvins (a measure of temperature, so you are not wrong). Heating a black body to 20 000 kelvins causes it to radiate a blue light. When we say a bulb is rated at 20 000k we talk of it approximating this same blue colour.

Correct.
Now give this some thought. The light from the solar dome is natural light, said to be about 6000k at the surface of the water. As this light penetrates the water so the colour temperature changes. The deeper the measurement is taken the higher the colour temperature.This is due to the warmer colours been filtered out.

Now we know that the pigmentation of zooxanthellae corals are a defence mechanism against UV and that T5's and Halides emit UV. Natural light has the correct amount of UV required else these corals would not exist.
My question now is. Is it not feasible to use low wattage UV globes and filter the UV to change the corals colour?

 

[Bob the (reef)builder]

Are you suggesting that we use the UV globes as well as the light from a solar dome?

If so I think you would be adding too much UV or more than necessary as the unfiltered sun has penty on its own, and possibly too much for many deeper level corals.

If you're talking about adding UV to our more normal setups, I have thought about it and considered black lights, as have some others. I never tried it, and haven't heard of any results which make me assume that there haven't been any positive ones, but maybe my ear has not been close enough to the ground. If there had been though the hobbie light producers would have probably jumped on the band wagon by now.

I think that the concept of UV producing colour is somewhat debated, or certainly how much it achieves is debated. I think that far more coral colour is got by simply providing more PAR causing the number of Zooxanthellae to be reduced thus not screening the base colour to the same extent.

 

[Nemos Janitor]

Ok. My thinking is similar. But I do not think the UV thing has been properly researched.
However the solar dome reflects the light and concentrates the UV. Is this not perhaps why the colour of corals under a solar dome lighting system seem better and reported growth more rapid?
This is one that will be debated over and over. But i will most definitely pursue both avenues. It will make a very interesting experiment. Thanks for your thoughts.

 

[Bob the (reef)builder]

It might also be that with solar lights the corals may be subjected to full sun, maybe with a par reading of 1900 for even a short period, even half an hour or so and then adapt to that extreme to protect themselves from the UV or sheer brightness of light during that time.

The nature of very changable light under solar domes may lead to bright colours that our more stable electric lights of 300 par don't.