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h2oaggie 07-20-2011 01:39 AM

29 gallon LED build
I want to upgrade the lighting on my 29 gallon from a 2x24W T5HO fixture. I mainly dislike having dark ends of the tank where the 24" fixture is shorter than my 30" tank.

I have taken my inspiration from one of Hoppy's builds. I plan on using 2 2" wide aluminum channeling to house 7 cool white CREE XP-G's, for a total of 14 LED's. I had intitally planned on using 65 degree optics, but I only want to suspend the fixture 6-12" above the water surface. In talking with Rockhoe14er, I have come to realize the optics might be unnecessary. LED's will be spaced 4" apart, and the two rows will also be 4" apart. This will allow for the most even lighting on the 30"X12" tank without using 20+ LED's. I will be using a dimmable Mean Well driver to achieve the PAR I desire (80-100 at the substrate).

Is there anything I am missing? Any suggestions?

I am a total newbie when it comes to electronics, so thanks to speedoflife (local TPT member) and Rockhoe14er for your help so far.

My RapidLED cart looks like this.
CREE XP-G R5 Cool White 3W LED on Star $5.00 14 $70.00
10K Ohm Linear Potentiometer $3.50
10V AC Adapter $10.00
Mean Well ELN-60-48D dimmable driver $34.00
3-Prong Power Cord $2.50

Sub-Total $120.00

Here is a very crude mockup of my planned fixture.

speedoflife 07-20-2011 02:00 AM

60 degree optics.
6 inches above the tank.

h2oaggie 07-20-2011 02:02 AM

Haha thanks, you just had to show off your GoogleSketchUp work! Still trying to decide on the optics...

jcgd 07-20-2011 02:16 AM

Speedo life, can you do a sketchup with no optics for comparisons?

60 degree optics look to have perfect spread.

reybie 07-20-2011 02:23 AM

What's the rendering like without the optics?

Edit: Oops, late to the party, justin already asked the same q.

speedoflife 07-20-2011 02:48 AM

Don't mean to sound arrogant, but it's not really worth doing that rendering. I can if you really want it, but you can easily see from this picture (stolen from ) that it essentially spreads the light everywhere. However, this is misleading, as one can see by the intensity vs angle graph on the LED's data sheet how much more intense it'd be at the center. I suppose one could do a sort of rendering combined with the intensity vs angle incorporated, but I'm not that smart.

Graph at bottom of page 6:

speedoflife 07-20-2011 02:51 AM

40 degree optics.
12 inches above the tank. Yeah it's only 5 LED's but good for comparison purposes.

Rockhoe14er 07-20-2011 05:28 AM

Looks really good. Do you have a multimeter? you might want to get one if not.

Hoppy 07-20-2011 05:41 AM

Try using this: to see how much PAR you will get with that LED setup. I did a quick try and it looks like you get about 40 micromols of PAR with 1000 mA current.

cggorman 07-20-2011 12:24 PM

After having worked with six different Meanwell driver, I would say a multimeter capable of measuring current (2 amp max is plenty) is essential. They ship all over the place.

h2oaggie 07-20-2011 02:07 PM


Try using this: to see how much PAR you will get with that LED setup. I did a quick try and it looks like you get about 40 micromols of PAR with 1000 mA current.
Interesting, I just played with that formula as well. The PAR values I calculated were significantly lower than what I expected, especially after talking with Rockhoe14er about his build.

I guess 65 degree optics are a go. I can always dim the LED's down to the desired intensity, but once I build the fixture there is no adding more light without serious adjustment.

IWANNAGOFAST 07-20-2011 04:13 PM

I highly recommend you run optics, you want to reduce the amount of light hitting the glass as much as possible. I didn't on my fixture and oh my goodness the algae that grows on the glass is ridiculous, if I don't scrape the glass, it only takes 2 days before I can't even see into the tank anymore.

I'm redoing my fixture right now, adding 60degree optics and dimmable drivers. Wish I did this from the start!

reybie 07-20-2011 04:28 PM

All this LED build threads is making me more interested in putting one together. I will have to keep an eye out locally for aluminum channels.

h2oaggie, is your fixture going into a canopy or standalone?

h2oaggie 07-20-2011 04:41 PM

It is going to be stand alone. The channeling should look good enough on its own after a little buffing. It will look just like this but two rows rather than 4.

Hoppy 07-20-2011 04:56 PM

I think I would use 40 degree optics, to get more PAR at the substrate, to reduce the light striking the glass, and to enhance the "shimmer" effect, if you want that. And, I would put the light a foot above the tank, because it looks good there, and it gives you good access to the tank for maintenance.

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