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  Topic Review (Newest First)
05-22-2012 06:58 PM
WingoAgency 12 Cree 3W-4.5W LEDs with 40 degree optics are too strong for a 20L. Consider 60 degrees for the most part and use 90 degree lens for the 3rd and 5th column assuming you are spacing it like your diagram.
05-22-2012 03:43 AM
jcgd You just want to have as much flexibility as possible. Then the final setup is simply whatever works best.
05-22-2012 03:41 AM
FrenchFry Thank you to everyone for the tips. I just found out that I have to move (landlord is selling), which means the tank will be torn down and set up in a different location, so I will probably be able to set the LEDs up much higher. I will build the fixture as soon as I have settled in.

This may be a lot easier to build if the lights are 12 inches from the water instead of 8.
05-18-2012 06:30 PM
jcgd Cool white are almost a perfect kelvin IMO. So if you add all those warm whites you'll want some blue to be able to balance it out. I have nice control over my color with 28 cw, 12 rb and 12 neutral white. Next time is use normal blue instead of royal.
05-18-2012 06:28 PM
jcgd Keep in mind that 18 LEDs over a 20L will look like a fiery inferno. I put 52 LEDs over my 6'x2' tank and before I put optics on I couldn't watch tv in the same room. That's with the LEDs running at less than half power.

Not saying you don't want all 18, just saying there probably won't be really noticeable dark areas.
05-18-2012 06:11 PM
Originally Posted by FrenchFry View Post
If there are 5 LEDs per row spaced four inches apart, then the three rows would be centered over the middle 20 inches of a 30 inch tank. With 40 degree optics, wouldn't that mean the ends of the tank would be quite dark?
The ends of the tank would not be as bright as the middle, but they wouldn't be dark. You could increase the number to 6 per row and brighten up the ends a bit. Remember, light will reflect off the end glass to increase the brightness near the ends, too. 18 total LEDs will be a bit easier to fit to a couple of LED drivers too.

If you want to use 60 degree optics you will have to either move the light closer to the tank or switch to Cree XP-G LEDs.
05-18-2012 09:45 AM
jonbar1 I'd recommend Neutrals over Warm whites but in the same ratio you are using. I'd probably go with 60 or 80 degree optics and make sure you don't use superglue to attach them! Soldering these guys is very easy, just pre-tin the wire and pad on the star, hold together and apply heat. 60/40 rosin core solder from radio shack worked well for me and is inexpensive.
05-18-2012 05:27 AM
FrenchFry If there are 5 LEDs per row spaced four inches apart, then the three rows would be centered over the middle 20 inches of a 30 inch tank. With 40 degree optics, wouldn't that mean the ends of the tank would be quite dark?
05-18-2012 04:33 AM
Hoppy That calculator doesn't give a good result if you space the rows a lot further apart than the LED spacing. If you want to use evenly distributed LEDs over the whole top of the tank, I would use 3 rows of 5 LEDs, spaced 4 inches apart, with the rows 4 inches apart. And, I would use XR-E LEDs, with 40 degree optics. At about 600 mAmps you should get 60 micromols of PAR. It would probably take 2 LED Drivers, but maybe not. That should give you very uniform light, and the XR-E is fairly cheap now. DealExtreme is a pretty good store to deal with too.
05-18-2012 01:29 AM
FrenchFry Ok, so here are some images of the basic setup, and then 3 different options for light layout. I have pretty much ruled out option 3, but I'm undecided between options 1 and 2. It seems like staggering the lights would get more even coverage.
05-17-2012 11:52 PM
FrenchFry I have been using this calculator, and so far it has been very helpful, thanks! I did not expect 60 degree optics to reduce par by half, but in using the calculator yesterday I think it said about 37 Micromols for two rows of LEDs at 4 inch spacing with 60 degree optics, and 90 micromols for 40 degree optics. Is that right?

Unlike a scaped aquarium, this tank has rows of plants from front to back instead of side to side. As a result, the front and back have to be lit pretty evenly. I'm also worried about light getting lost in the middle due to the seam on the glass lid. With a single row of lights in the center, I would expect the plants near the glass to not receive much light with 40 degree optics, is that correct?

If the light is placed 8 inches above the tank at 4 inch spacing (two rows), will the spotlight effect be dramatic? The tank has so many plants that there is not much open water space to really see beams of light on.

Also, would a glass lid reduce or amplify spotlight effect?

Could I use a mix of optics, like 40 degrees near the ends tho reduce light on glass and 60 degrees near the middle?

05-17-2012 10:54 PM
Hoppy Play around with the calculator in this thread:
I would use a 3.25 inch spacing of the LEDs, one row, about 8 LEDs, Cree XP-G, either all cool white or 5 cool white and 3 neutral white. At 18 inches distance, with 40 degree optics you should get about 60 micromols of PAR, high light, at 700 mAmps current. If you want to use a knob to control the light intensity, use the D version of the Meanwell driver.

A single length of 1" by 2" by 1/8" or even 1/16" aluminum channel should work fine for the heatsink, with no fan. I would put the LEDs in the inside of the channel, to help shield people's eyes from the LED glare.

I haven't used the solderless connectors, so I don't know how well they work, but if you are uncomfortable with soldering, I feel pretty sure you would be satisfied by the results with the solderless kit.
05-17-2012 08:20 PM
FrenchFry Thanks for the quick response! I have made a few diagrams that I will upload when I get home to a computer, and once I figure out the answers to all of my questions, I will document the construction process.
I still have many questions about the lens color, 40 vs 60 degree optics, whether to use the meanwell 48 P or D (read the spec sheet, still have no idea of which to go with), whether light coverage would be adequate, and where to get my heat sink. I still have a lot to learn, and all advice is greatly appreciated.
05-17-2012 07:48 PM I've got to advise soldering things together. Solder less is neat in concept, but the contacts will eventually corrode and either lose contact when jolted, or simply lose contact some day.
With today's lead free solders, corrosion should never be an issue. LED stars are easy to solder to.

Depending on your heatsink, a fan probably won't be necessary. I use two panels of 12 emitters running at 670mA on my 70g. It gets warm enough that you can feel it if you touch it, but only just warm.

I used a 50/50 mix of warm white and cool white. I like it and so do the plants.
You may not want optics on the emitters on the ends. Try it with and without.

One very important thing, Post a picture and details when it's done. Lots of folks will benefit from your experience. Even those of us who've gone LED can benefit from the experience of others.
05-17-2012 07:32 PM
DIY LED kit for a heavily planted 20L (solderless?)

I am in the planning stages of building an LED fixture for a 20 L tank (30x12x12) that is planted very heavily. While I do have a soldering kit, I was quite intrigued by the 12 Solderless LED Retrofit Kit Dimmable offered by RapidLED as it seems a lot easier.

The fixture itself will be hung from a shelf which is 8 inches from the surface of the water. I was thinking of using two aluminum u-channels (2x1) so the fixture can double as a heat sink. To maximize lighting at the substrate, 40 degree optics will be used.

So, onto the questions. This kit comes with 2 LED terminals, each of which is only 4 inches long. In order for my setup to work, I will have two row of LEDs, one in each u-channel. As a result, it seems to make sense to me to have one of the LED terminals near each channel (since it is only 4 inches I was thinking each terminal could go in the space under the cross beam that connects the channel at each end). This would mean that the wire from the terminal to the LEDs would be quite long (closer to 30 inches).

- there are some 3.5 inch extension wires that can link an LED to the terminal. Would it be possible/safe to modify these wires to make them longer (30 inches max)?
- of the driver is at 700 mA and the fixture is at 8 inches above the water level and has 40 degree lenses, will coverage be sufficient with 7 cree xp-gs in the front and 6 in the back? Thank has high co2 and ferts.
- would a fan be necessary at 700 mA?
- what mix of bulbs would you recommend for freshwater? I was thinking 5 warm white and 8 cool white, unless neutrals should be thrown in the mix?
- should lenses be white or black?

Any advice you have for a total LED building beginner would be greatly appreciated. The solderless kits are only $10 more than the soldering ones, which is why I am trying to see if that will work.

If not, I will do two rows of 7 and do the soldering.

Thanks in advance!

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