Questions about lighting...

[woofwoofgrrl]

I'm considering getting my nerd on and doing a DIY LED light build. I'm finding lots of LED's in the right K range, but I'm wondering how many Lumens I should shoot for? Obviously WPG doesn't work as an accurate guestimator with LED's since they are much lower power. Brightness wise, what's considered low, med, and high light ranges?

Thanks!

 

[tyspot1000]

Good luck with the build! I have a Marine land LED Double bright lighting system that is 450 Lumens, It is able to support Low to Moderate light plants (My moderate light plants are doing great), so just a heads up.

 

[BigJim]

I'll be posting my 24" 30W DIY LED fixture tonight or tomorrow. I used ten LEDs that are rated up to 107 lumens a piece with hopes that the fixture will work for a 20H high-light planted tank. I don't know what they're putting out, but the fixture is blindingly bright.

I really struggled to find any correlation between the fluorescent Wpg rules and LEDs. Lumens aren't a very good measure, but that's where I started too. I didn't get very far before I scrapped the lumen approach. I was getting absurd numbers of needing fifty 3W LEDs for a high-light 20g tank. Ten 3W LEDs is incredibly bright. I'd have to wear my welding mask to look at fifty.

I decided to go with empirical data instead. I found some LED build threads on reef forums. One in particular compared LEDs to T5HO lights and the LEDs won hands down in a PAR measurement. I'll look for the link and post it in my build thread if I find it. PAR (Photosynthetically Available Radiation) is the best measure of light effectiveness I've found, but a PAR meter is expensive.

Ziggy used twenty 1W LEDs, ten white, ten blue, on his 54g corner planter with great success: http://www.aquariumadvice.com/forums/f24/ziggys-corner-planter-135620-6.html I haven't kept up on his plant selection to know exactly what his lights will support, but the tank looks fantastic.

Sorry for the ramble, but I don't know of any Wpg type rules for LEDs yet. LEDs are relatively new to the aquarium scene and there's a lot still to be learned.

 

[woofwoofgrrl]

BigJim, which LED's did you go with?

I spend my morning sucked into the Digi-key website looking over the mindbogglingly huge selection of LED's. I've thought about going the super bright LED route, because the frequency distribution of the warm whites looks pretty good in comparison to the site I was reading that analyzed the frequency needs of plants and fish. (Aquarium Lighting; Kelvin, Nanometers, PAR, Bulb, Watt, MH, LED, Light Basics.)
Although I was leaning more toward 6 than 10! LOL!

I am concerned about the overall brightness factor for the fish though. There were warnings on some of them not to look directly at the light to prevent retinal damage! Although I suppose the water would diffuse the light enough to keep from blinding them.

With regular LED's the graphs look like there isn't much in the 625-725nm spectrum and I'd have to supplement with red LED's. My tank is a 30 long, so I don't have to worry about getting the light to any dark depths, so I think I could go this route as long as I get a wide viewing angle.

I need to find the happy point on the cost/frequency/brightness curve!

Of course, I'd really like to see something that tells me how many lumens of each frequency range I need to keep various plants happy. That way I could fine tune to the individual LED level. But I guess I'm nerdy that way.

Send me a link to your fixture post when you put it up! Thanks!

 

[BigJim]

I went with Cree XR-E Q5s in Cool White.

I had the cool white vs. warm white spectrum discussion with someone else on here previously. I haven't seen a warm white high-power LED in person, but I've seen warm white LED Christmas lights and I've used warm white bulbs on my tanks before and I greatly prefer the cool white look. I figured if I needed some red, I could add it.

 

[fort384]

PAR definetly seems to be the "going measurement" to figure out what you need in an LED fixture. Ziggy's tank in the thread linked above is very successfully growing medium light plants with his build.