DIY LED - selecting the right wavelength

Liron Mishal · Feb 7, 2019

Hi guys,
i'm about to have a go on a DIY LED fixture.
my tank is 2 foot tall and 4 foot wide , and is just about to receive it's first fish.
I was thinking that it would be a good time to build a LED fixture before pooting some corals in, so i need your advice:
I was thinking about 4 50W LEDs, 2 white - 10000k and 2 450nm royal blue LEDs.
the LEDs will be mounted on a long aluminum profile with all the electronics in it and each LED will have a 60 degrees glass lens.
I already have the royal blue LEDs and built the electronics for it with dimming capability, so i dont think that it would be too much terms or PAR (or watt, or lux or whatever it means ;Dead)

the question is, would it be beneficial to add some red to it? also, is 450nm the right choice for such a fixture?
I *tried* to read some of the articles around here but I cant seems to wrap my head around it for the life of me

Thanks.
Liron

Ron Reefman · Feb 7, 2019

Liron Mishal said:
Hi guys,
i'm about to have a go on a DIY LED fixture.
my tank is 2 foot tall and 4 foot wide , and is just about to receive it's first fish.
I was thinking that it would be a good time to build a LED fixture before pooting some corals in, so i need your advice:
I was thinking about 4 50W LEDs, 2 white - 10000k and 2 450nm royal blue LEDs.
the LEDs will be mounted on a long aluminum profile with all the electronics in it and each LED will have a 60 degrees glass lens.
I already have the royal blue LEDs and built the electronics for it with dimming capability, so i dont think that in would be too much terms or PAR (or watt, or lux or whatever it means ;Dead)

the question is, would it be beneficial to add some red to it? also, is 450nm the right choice for such a fixture?
I *tried* to read some of the articles around here but I cant seems to wrap my head around it for the life of me

Thanks.
Liron

Having good lighting is critical if you are going to have coral in the tank. PAR is Photosynthetically Active Radiation which simply put is the total amount of light that can be used for photosynthesis by plants and algae. Most terrestrial plants and algae use more red and yellow spectrum. Some very important algae use much more blue spectrum than any other. PUR is Photosynthetically Usable Radiation which is the specific spectrum than any particular plant uses for photosynthesis. But with a variety of different corals using a variety of different zooxanthellae, it's difficult to determine an accurate PUR list. And there isn't really a good way to measure PUR since the spectrum that would need to be measured is always different. So most people just use PAR and there are a variety of meters that can measure that range.

The most important thing you need to consider is that light you use is good for the coral. Blue spectrum from 400nm to 460nm is what most coral's zooxanthellae (symbiotic algae) use to do photosynthesis which does most of the feeding of the coral itself. Limiting your light to a single blue spectrum can work, but it will be very good for many corals and less helpful to some others. Having multiple spectrum leds in the violet to blue/green range would be far more useful for the coral.

You will have white leds which make viewing the tank more natural to our eyes. That white light has red/green/blue components and should provide all the red spectrum the tank will need. The coral polyps themselves (not the zooxanthellae) use spectrum other than blue to produce pigments, protiens and other chemicals important for the coral's health.

Four 50w fixtures over a 4' long tank is probably about the minimum for most corals. You could do well with zoas, softies and many lps corals. Some lps and many sps corals will probably survive in those conditions, but growth would be slow IMHO. And it is exactly that, an opinion. I have a 40g cube (2'x2'x20") and I have about 200 watts of various blue and violet leds I run at 90% power during a 6 hour midday and 150 watts of white leds that run at 20% power for the same 6 hours. Although most of my tank is zoas and rock flower anemones, I do have some lps and sps corals which are all growing. So I have half the tank you have and more wattage which provides more PAR than your proposed lighting system. I think you'd be better off with 3 or 4 of your blue leds and 2 of the white. Set them over the tank from left to right as blue, white, blue, blue, white, blue.

I hope this helps some?
Good luck. I worked on some diy leds and found the fixtures available today to be better and cheaper than I could make.

Liron Mishal · Feb 7, 2019

FANTASTIC!
that's exactly what i was looking for!
so, i need to order some more LEDs then.
Following your advice, I should go for this setup?: 430nm - white - 450nm - 450nm - white - 430nm

oreo54 · Feb 7, 2019

10,000k or any high whites is old school..

not a lot of anything but blue..

Liron Mishal · Feb 7, 2019

@oreo5457 not sure i understand..
Reduce white led wattage?
Reduce color to 6000k?

topjimmy · Feb 7, 2019

Take a look at pre-made pucks like blueacro

oreo54 · Feb 7, 2019

Liron Mishal said:
@oreo5457 not sure i understand..
Reduce white led wattage?
Reduce color to 6000k?

https://ecotechmarine.com/wp-content/uploads/2016/07/ReefWholesale_CoralLab.pdf

Worth a read...

n21benson · Feb 27, 2019

Has anybody ever tried using 12V LED Blue lights? Seen a 4 x pack at the local hardware store. Thought they may compliment the current T5's I have on the tank.