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CREE XM-L DIY High Powered LED Aquarium Light

By keno | March 30, 2011

CREE XM-L DIY High Powered LED Aquarium Light

A Word of Caution:

This project involves the use of electricity, power tools, and high power LEDs. Before you tinker with LEDs or any electrical materials, be sure you understand the risks involved. This series of articles was created simply to share what I’ve done. These are not verified instructions. I take no responsibility for any harm caused to you, others, or to your property as a result of the info contained in these articles.

So I had to try them, them being the CREE XM-L (T6) LED’s. The CREE XM-L (T6) LED’s are rated at 1000 lumens @ 3 amps. I wanted to see just how bright are these newer CREE LED’s. The brighter the LED’s, the less LED’s you would need to get the same or higher level of lighting. Getting the CREE XM-L LED’s was easy. I ordered them back in December 2010 and I had them by the end of the month. The harder aspect of this project was in finding the right LED power supply. I needed an LED power supply that could supply the 3 amps I was looking for. I was lucky that my supplier was able to get me an early release of the Mean Well HLG-150H-54B LED power supply. This supply has a rated output of 54Vdc @ 2.8 amps. Not quite the 3 amps but close. It is a constant current device / variable Vdc device as with the previous Mean Well LED power supplies I have used on past DIY High Powered LED Aquarium Lights. The power supply could handle up to 16 of the CREE XM-L LED’s, but I opted to have 14 LED’s. Why 14 when the LED power supply could handle 16. Well I had ordered the 14 CREE XM-L LED’s prior to getting the LED power supply. The other LED power supplies I was looking at could only handle 14.

I had several goals of this latest project.

Single Heat Sink

In the past I had used smaller sized heat sinks and used aluminum angle brackets to hold the heat sinks in place. My thinking was I could cover the same amount of space with less weight. With these CREE XM-L LED’s I felt that heat dissipation was more important, plus installing the heat sink would be easier since I didn’t need to mount all the smaller heat sinks together. Using the one heat sink was much easier to mount, plus there was a huge time savings in not having to build the heat sink assembly.

Hanging the Fixture

For this project, I planned on hanging the fixture above my aquarium. I planned on using 3/4″ metal electrical conduit as my hangers. The design for the hangers began during the design phase of my aquarium stand. I decided to build my own stand and mount the hangers to the back of the stand during the build process. I good friend of mine Darin was able to get from work two key pieces of equipment to bend and cut the metal conduit. A pipe bender and a portable band saw.

We bent and cut the pipe to the size we needed and using conduit clamps mounted the conduit to the back of the stand. As part of the design, I wanted the AC power cord to run through the conduit. So we drilled the holes for the eye bolts and the hole for the AC power and pushed the power cable through the pipe. The power cable I used was a piece of 3 conductor cable that was left over when my pool was installed. The cable was used by the installers for my underwater pool lights. There was a piece they were going to throw away, so I saved it. I mounted a plug on the end of the cable inside the stand and on the end above the aquarium, I mounted a molex type connector. I mounted the matching connector to the power cord coming out of the light fixture. So once the light was hung in place, I could connect the AC power to the light fixture with the molex connector.

For the light fixture, I decided to install eye bolts into the fixture to hold it above the aquarium. I also wanted an easy way to level the fixture, so once I had the holes drilled into the fixture, I epoxied nuts on the inside of the fixture. I then planned on using the same nuts on the outside of the fixture on the eyebolts. This way I could loosen the nuts on the outside of the fixture and twist the eyebolts in or out to level the fixture. Once it is level, I could then tighten the nuts on the eyebolts against the fixture for a snug fit.

Dimming the HLG-150H-54B

The Mean Well HLG-150H-54B LED power supply can be dimmed three different ways. A resistive value between 0 and 100K ohms, a dc level between 0 and 10 Vdc or a 10 Volt PWM signal. In the past I have used the 0-10 Vdc signal for dimming, for this fixture I decided to use the 0-100K ohm resistive feature. To control the dimming I picked up a 100K ohm potentiometer. With any of the dimming methods, this particular LED power supply will not go to 0 amps on the output. What that means is that you can not dim the fixture to the point of the LED’s turning off. For me, that was not an issue. You can dim the fixture to a pretty low light level. I only use the dimming feature when I am adding new fish to the aquarium anyway, and if I need to turn it off completely, I just turn off the AC power switch.

12 Vdc Power Supply

In my previous builds I would use an external 12 Vdc regulated power supply. This 12Vdc power supply would perform 2 functions. The first function was to supply 12Vdc to my fans, and the second was to supply the 0-10Vdc dimming control for the LED’s. For this fixture, I didn’t need the 0-10Vdc control, but I did need 12Vdc for the fans. Yes, you can get 120Vac fans, but there is a wider selection of 12Vdc fans available. Also, I didn’t want an external 12Vdc power supply since this fixture was going to be hanging and I didn’t want the extra cord. Yes, again I could have found a 5 wire conduit, but I had the 3 wire conduit sitting in my basement. So I found a 12Vdc brick style power supply at the same place that I got my 12Vdc fans. The nice thing with this 12Vdc supply is that the output has a male molex type connector on it. I have a bunch of molex connectors which would make the assembly process easy. As a side note, the 12Vdc power supply also has a 5Vdc output if you need it.


Mounting the CREE XM-L (T6) LED’s to the heat sink was done using a double side thermal tape. The part can be found at digikey.com and it’s part number is Ber159-ND. It comes in a 10″ x 10″ sheet and you just need to measure and cut the tape to size. The LED’s were soldered using a product called SOLDER-IT at my local Lowes store for $3.47. The build process went smooth as usual.

Then It Happened

I had the fixture all put together and I had run through some testing, on/off tests and heat testing at my kitchen table. Everything was looking good, so I decided to mount the fixture above my aquarium. My son Andrew and I put the fixture in place, made sure everything was level and plugged the light in. The light came on and everything looked just fine. Until, 20 minutes later the light went out. I checked power and the fans were still running, so I knew that I still had 120Vac going into the fixture. Good thing for the molex power connector for the 120Vac. We took the fixture back out and I tested my LED connections and everything looked good. So I grabbed a spare ELN-60-48D power supply that I have and rewired the LED’s to it. The LED’s turned on just fine. So, it looked as if the Mean Well HLG-150H-54B LED power supply had gone bad. The next day my supplier had a Mean Well engineer contact me to help troubleshoot the problem, and he too confirmed that the power supply had gone bad. Mean Well shipped me a replacement power supply and now the fixture is running just fine.

In Conclusion

The amount of light from such a small number of LED’s is amazing. Cost wise the new fixture with the Mean Well HLG-150H-54B LED power supply costs about the same as my previous fixtures using the CREE XP-G R5 LED’s. The big difference is in the assembly process. Only one LED power supply vs 2 LED power supplies. The dimming circuit is only a potentiometer vs using the 12Vdc power supply and creating a voltage divider circuit to get 10Vdc for the dimming inputs. The biggest plus for me only having to solder 14 LED’s vs 28 LED’s. Like I’ve said before, I hate soldering. Would I build another, absolutely. I am planning on setting up some plant grow out tanks. I am planning on building some new fixtures. I figure that I will put the CREE XM-L (T6) LED’s fixtures on my view tanks and take the previous CREE XP-G R5 fixtures and put them on my grow out tanks. Additionally, the Mean Well HLG-150H-54B LED power supply can handle 16 of the CREE XM-L (T6) LED’s. So the new fixtures will have 16 LED’s in them.


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Topics: CREE xm-l DIY LED Aquarium Light, CREE xm-l T6 DIY LED Aquarium Light | 17 Comments »

17 Responses to “CREE XM-L DIY High Powered LED Aquarium Light”

  1. Ed Says:
    June 12th, 2011 at 9:53 am

    I am setting up a cichlid and plants tank 115G 31″ deep. I want to go with LEDs. Do you think 24 CREE LEDs 12 cool white XP-G r5 and 12 XP-e royal blue will be enough light for my depth of tank? I wanted to ask someone with fresh water LED experience. Your setup looks great.I hope mine looks half as good when I’m done.

  2. keno Says:
    June 12th, 2011 at 7:21 pm


    What’s the dimensions of your tank?

    Are you raising African or South American Cichlids? Depending on the type will determine the type of plants and the level of lighting you will need.

    Why do you want royal blue LED’s? Are you thinking of using them for a night light effect?

    Royal blue or blue will not help with a fresh water planted tank. SW Corals need the 420-470nm wavelengths, but freshwater plants do not need them. Me personally, I would not add the blues, unless you want a night light effect. I would put the money into more CREE XP-G r5 LED’s.

  3. Vick Says:
    June 21st, 2011 at 2:21 am

    i have a 4 foot tank with a depth of about 20 inches. I plan to use the Meanwell HLG-150H as you did. In your opinion, would 16 XM-L’s be enough for a 4 foot tank or would i need to get another driver and more LEDs?

  4. keno Says:
    June 22nd, 2011 at 10:25 am


    I have 14 of the CREE XM-L’s on my 4 foot 75 gallon aquarium. 16 would be way more than enough. I had had my light fixture at the very top of the tank (~20inches). I have since raised it a few inches so that it is now 23 inches off the substrate. I am thinking of taking it up a couple more inches. You will have no problem in going through 20 inches of water. I would not add any additional LED’s.

    I raised it because I felt it was too much light for the tank. At 23 inches the plants are still showing great colors. I feel that at 25 inches it should be the ideal spot.


  5. Michael Says:
    January 19th, 2012 at 4:48 am

    Your work is very impressive and thanks for taking the time to post it. I’m looking at trying the same thing and just want to make sure that you used the CM-L “cool” LED’s. The ones that run between 8,300 – 5000 CCT (K)?


  6. Michael Says:
    January 19th, 2012 at 4:49 am

    Sorry about the typo. I mean the XM-L’s

  7. Dhruv Says:
    February 4th, 2012 at 1:45 pm

    Hello Keno,
    Your articles on led lighting are really inspiring and easy to understand. I am planning to make similar hood of XML Leds like yours, for my planted tank. Dimensions are: L-48 inch, W-18inch & Depth of 15inches. How much XML’s do you suggest? Would 10 be enough? or should i make an XPG fixture like yours for 55gallon coz XML’s are a bit costly here in India.

  8. Brandon Says:
    February 8th, 2012 at 11:03 pm

    Where did you get a heatsink that was 4 feet long? I plan on building an LED fixture for my salt water tank and plan on using white XP-G LEDs and blue XP-E leds and have been looking for a heatsink or something like on that is 4 feet and cheap and will do the proper heat disipation.

  9. keno Says:
    February 11th, 2012 at 10:01 am


    I get my heatsinks at http://www.heatsinkusa.com. They have various widths and lengths you can get. I have been using the 5.886” width mostly because that width fits my fixtures that I use.

    Any other questions, just let me know.

  10. keno Says:
    February 11th, 2012 at 10:05 am


    Whether you go with the XM-L’s or the XP-G R5 LED’s I would use 14 of either. I have a fixture with 14 XM-L’s on a 75 and a fixture with 14 XP-G’s on another 75 both work well. I am building a new fixture for a 75 the will use 14 of the XM-L LED’s I plan on only running them at under 2A. 3A is way too high and not needed.

  11. keno Says:
    February 11th, 2012 at 10:07 am


    Yes I use the cool XM-L with a T-6 binning.

  12. Mohan Says:
    May 9th, 2012 at 2:15 pm

    Hi Keno, nice light you have there. Well done. I need some help here.
    I’m planning to convert my existing T5HO light set (2x39w) with XML T6 LED’s. My setup is 36″x18″x18″ and may change to 36″x24″x24″ soon. Appreciate your advice on how how many LED’s running at what amp will be appropriate for my setup. I understand the XML viewing angle is 125 degree. Does a single strip align to the centre of the tank at 6″ gap between LED sufficient? This is just my rough estimation. Thanks a lot…

  13. keno Says:
    May 16th, 2012 at 8:16 am

    As for the amp level, on my current XML setup I am only running them at about 1.7amps. I found that running them higher burned out the LED’s. Most of that was due to insufficient heat transfer from the XML’s to the heat sink. Also there is no need to run them any higher in my opinion. On some of my tanks, I have started to reduce the current (dim the LED’s) to see if that has any positive affects on the plants. I am seeing that the plants are growing just fine. I did use a PAR meter to measure the light levels at the substrate as my form of measurement. I haven’t measured the current levels.

    As for the number I would go with 7 LED’s straight down the middle of the tank lengthwise.

    I have also started testing using a mix of LED light spectrums. Right now I am using a 50/50 mix of the XML-T6 and the XML-T3. I have been looking at the light spectrum needs of plants and trying to fine tune the light output to provide a wider spectrum. So far the testing has been very positive. I do need to get an update article out on this subject.

  14. Mohan Says:
    May 16th, 2012 at 8:27 am

    Thank you very much keno. I’ll be waiting for your article update on mix of led light spectrum and the spectrum usage by plants.

  15. Jonathan Says:
    July 23rd, 2012 at 10:34 am

    Where did you buy the LED’s? Would you ever consider building one of these on commission for my 75?

  16. Jimmy Says:
    August 26th, 2012 at 11:42 am

    Keno, your work has motivated me to build one. I have a 29g 19hx30wx12d with lighted hood that accommodates 1xT5 – 24″. I’m planning to purchase a 24″ heat sink and add 10qty CREE XM-L – Cool White. Would you recommend a Mean Well HLG-100H-36B for my application? I will use the same potentiometer that you have in your project.

    Your expert feedback is appreciated.

  17. Jimmy Says:
    September 9th, 2012 at 10:24 am

    Inspired by your work, mine is finally built. 26″L x 3.5″W heatsink, 10qty CREE XML Cool Whites, 100k ohm potentiometer from Radio Shack, and Mean Well HLG-100H-36B. I learned a fan isn’t required running below 40% power. Thank you for posting this dyi tutorial up.