View Full Version : The fundamental problem with LEDs

04-02-2010, 10:55 AM
There are quite a few threads on building LED lighting for an ATS. Some getting very long.
That is great. We will get there. LED lighting is worth the time to solve.
But for all those new to this, I really wanted to post a short separate topic on the real problem why most builds do not work well or at all.
And really emphasize : Built wrong, even if it looks great, it will FAIL!!!

The problem is in the details of the light spectrum.
If you just look at the usual color temperature, you might think a warm-white LED = warm white CFL = warm white incandescent.
And to a HUMAN, it would look pretty much the same.
Unfortunately, to algae, it is completely wrong.
A white LED is not even close to white. It is a blue LED with phosphors to cover SOME of the rest of the spectrum.
Actually, a CFL is not perfect either, but far better than an LED.

So here is a drawing of your typical warm white LED (orange), superimposed on the useful spectrums for algae.
The amplitudes are not really that important. What you need to look at is how the LED light covers the spectrum needed by the algae.
You can see that it does cover chlorophyll B fairly well. The blue spike lines up well, and the red is covered, although with a fair amount of waste.
But for chlorophyll A it is absolutely TERRIBLE.
Very little on either end. And that weak deep RED section appears to be the most important for algae.

So we get fooled by looking at it and thinking it looks great, where the algae says,"Who turned out the lights."
And even worse, there is some data that says the imbalance of that spectrum messes up the chemistry, and compounds the problem.
Plus, I have drawn one of the fairly new warm white LEDs. The older ones, especially if cooler, have even less on the upper end.

Get the picture. :)

ocean rock
04-02-2010, 12:18 PM
i will give you that " you know your stuff !" :D

04-02-2010, 04:05 PM
Generally agree with you but I would like to point out that different pigments can take in a good bit of light energy,

that is not represented as being used directly by chlorophyll a, and transfer the energy to chlorophyll a.

Hope this helps.

04-02-2010, 04:44 PM
Well, maybe. There is an argument that a lot of extra energy from those cartinoids (phycoerythrin?), without normal Chlorophyll A,
unbalances the reaction, actually makes things worse.
There are also Chlorophyll C, D, and E in algae.
It gets more complicated than I understand. I certainly know the engineering and the physics, but the biology is all from reading.
Plus, I have not seen any research SPECIFICALLY on green hair algae. And plants can be pretty different.

But I also rather wanted to keep it simple to really make the point.
There is a basic curve, where algae does not really use the spectrum from green-yellow.
Which happens to be where most of the energy of a white LED ends up.
A fundamental problem.

04-02-2010, 05:25 PM
Agree with you. If you like to know more and want to spend the time on it, I have been working my

way through this book.


A little old but who cares. Actually talks about algae quite a bit.

Hope this helps.

04-02-2010, 07:02 PM
Also I'm sure the folks at www.psaalgae.org (http://www.psaalgae.org) would know