Modern LED scrubber light

The big problem with white LEDs is that they are not white.
Not even particularly close.
There is a big spike in the blue at around 425 nm, and a broad spike around 560.
- Warm / Neutral / Cool are all a bit different, but still a similar concept.
Basically, they are actually a blue LED, which activates phosphors on the lens for the upper colors.

The problem is that the spike at 425 is a bit low for the blue aspect of chlorophyl.
And they drop off at 650 or so, which is a bit low for the red aspect of chlorophyl.

But the big problem with Red+Blue, as mentioned quite a few times in this thread, is that
since LED wavelengths are so tight, if you miss the key wavelengths, it may be completely useless.

My first Rev1 LED was a mixture. Warm white + red for the upper regions.
- That actually did fairly well. But it was simply too small for my tank.
For Rev-2, I am taking a shot at pure red + blue, with special deep-red, which hits chlorophyl better.
- Hopefully more optimal, but may end up worse. Results for the first few days are not fantastic.
There is a good chance I may need a rev-3. We shall see.
- One thing is that the deep reds and blues complement the warm white holes better than before.
- And I have warm whites from the first build of course.

Basic notes on algae and chlorophyl:
We are trying to grow green hair algae or similar such plant here.
Those plant types plant are generally seen in shallow water. Both fresh and salt.
As such, they expect fairly similar wavelengths as typical terrestrial plants.
Unfortunately, it is hard to say exactly what. Most of the spectral analysis that is seen is based
on what wavelengths the algae ABSORBS, which is not exactly the same as what it USES.

Corals, especially deeper water corals, are very different.
They have adapted to using much more of the blue end of the spectrum.
This is because most of the red end is gone by the time light gets to them.
Partly due to the weak absorption of red wavelengths by water itself, but more so by all the free floating algae.

So for the main tank, you want very little red, and lots of blue, to starve green algae, and grow coral.
For a turf scrubber, it is the opposite. We are deliberately growing the green, so want lots of red, and less blue.

Rygh, I here what you are saying. My thinking is that CREE spends a lot more time

and resources in making white(blue w/ phosphors) leds than any other led. Hence they are over

the top bright/efficient. Red leds are sometimes a different type of die.

They don't even make a colored xp-g. I might be wrong

trying to figure it out myself. Understandably the whole thread has mostly been about

what will be the most efficent ???

Thanks for any help.

I agree that cree seems to be the leader in lighting FOR PEOPLE.
They do a great job at the most efficient lighting for our eyes.
And even the "luminance" measurement includes a factor for the spectrum used by human eyes.

But all that has little correlation with what is best for algae.
And I think that fact is why a lot of LED driven ATS setups fail.
You get fooled by what looks to us light great lighting. But it is terrible for algae.

On the other hand LedEngin actually mentions this in their deep-red datasheet:
"The LZ1-00R205 LED emitter provides superior radiometric power in the wavelength range specifically required for plants’ chlorophyll a absorption."

For LED lights I put in around the house, I have definitely used Cree.

All that said, I cannot definitively say that what I did was necessarily correct either.

I've spent a lot of time pouring over spectral graphs about lights and LED's, LED grow lights, etc.

I suggest 470nm blue and 630nm LED and/or 6500k and 4000k. I think your missing the spectrum marks just a little bit.
Other marks to possibly hit are 430 and 660(you already have the 660's covered pretty much)

Cree does make a range white emmiter(think its 3 or 4 emmiters in different K ranges) and also an RBGW that has 4k white that would probably be good. prices? Probably not cheap.

I am a bit worried about the blue as well. The red I think is ok.

There is an extra problem that should also be emphasizes: The accuracy is terrible.
When ordering just a couple, you get what you get. It is rare be able to choose detailed bin code.
You have no idea where they fall in the bin.
They vary a lot based on current and temperature.
For example, my BLUE is from a very good vendor, but still may from about 440 to 490.

I am going to wait a few weeks for results.
But if it is not great, then I may try a "shotgun" approach.
Basically, add a bit of everything and make a fairly flat spectrum.
One downside is wasted power, but it is still a lot more efficient than CFL.
Another downside is that the optics become a bit tricky. You cannot have a lot of each color, so even
distribution becomes a pain.

I just ordered (8) xp-g warm white leds $63.73 (shipped) from cutter down under

XPGWHT-L1-7D2-Q5-0-01 Warm White 7D

Planning to combine them with some ledengin deep reds.

If they don't work so well I still have some of the best leds made right now.

If any one wants to do some R&D please do. This is getting expensive.

Will see if this helps.

Do you have a spectral graph on that one? I've seen warms with very tall "royal blue" spikes and ones with short "blue" spikes
"

http://www.cree.com/products/pdf/XLampXP-G.pdf (page 3)

XPGWHT-L1-7D2-Q5-0-01 Warm White 7D

................7d2.........................

is the bin # that describes chromaticity

http://www.cree.com/products/pdf/XLampXP_B&L.pdf (page 11)

Hope this helps

Yeah thats one of the ones with the small blue spike and the really high sweeping red spectrum. If its red your after then that certainly is the one.

I've got an itch to wire up the red and the blue that I think would be best and try it out on my scrubber inplace of one of the CFLs for a test. Gunna have to check cost on how much that experiment would cost me.