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My 75 gallon DIY LED CREE xm-l T6 update

By keno | December 15, 2012

It’s been awhile since I last posted an update.

In my first build of my CREE xml-T6 I used a Mean Well HLG-150H-54B LED power supply and ran the LED’s at 2.8 amps. Way too much current. In addition I only used  Thermal Pads instead of Thermal Paste.  As a consequence, the LED’s burned out in a relatively short period of time. A hard and expensive lesson.

 This LED formed a white film inside the LED dome. The LED would still function, but it’s output was diminished.



This one just burned out


So I decided to rebuild the fixture, this time using BJB Solderless LED Connector and #4 Self Tapping Screws. The beauty in these hold downs is that no soldering is required. Anyone who has followed my posts know that I hate to solder. Now I can build a fixture with little to no solder at all. The BJB Solderless LED Connector as the name implies requires no solder. You do need to use solid copper wire to run from connector to connector as opposed to stranded wire. I have also switched over to using a Thermal Paste (Arctic Silver) instead of the Thermal Tape.


 Here is just the BJB connector.


 Side view of BJB connector with LED star under it.

 Drill holes marked on heatsink.

Top view of BJB connector with LED star beneath it.


 BJB connector with LED star and Thermal Paste ready for screws.


 Screw points on BJB connector.


 Final look of BJB connector screwed down holding LED star.


At the same time since I was replacing the LED’s I decided to change out the power supply for one that would supply less current and I also wanted to try a mix of LED light spectrums to supply a better mix for my plants. So I used a Mean Well USA LPF-90D-48 and 7 CREE xm-l T6 LED’s and 7 CREE xm-l T3 LED’s.


Based off the following chart, the 2 ranges that plants need are the 400-520nm and the 610-720nm range.


This is also supported on this chart which was found in an aquarium magazine. The middle range the 520-610nm area is up for debate. I have read that this area promotes algae growth in aquariums.


 So now looking at my options for CREE LED’s specifically the xm-l series and based on this chart, I decided to use the T6 and T3 CREE LED’s. They would give me the maximum spectral outputs in the 400-520nm and 610-720nm ranges.

I don’t have any current images, but the plant growth has been great in my 75 gallon aquarium. In addition I was able to borrow a PAR meter from one of my fellow aquatic club members and I further adjusted my LED light output. I had been running the LED’s on full which is about 1.8 amps for the power supply that I am using. The PAR reading average in my tank was above 80 at the substrate level which is 21 inches below my fixture. I adjusted the PAR level to be around 50-60 now at the substrate level.

Any future LED fixtures I build will use the combination of T3 and T6 CREE LED’s.


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Topics: CREE xm-l T6 DIY LED Aquarium Light, DIY Projects, My 75 gallon tank | 4 Comments »

4 Responses to “My 75 gallon DIY LED CREE xm-l T6 update”

  1. Luis Torres Says:
    December 29th, 2012 at 4:31 am

    Hi there, i followed and studied your tutorials, because I want to make an aquarium and as such I have to make a led fixture.
    In this post i noticed that the Mean Well USA LPF-90D-48 only has 90W and you got 14 leds of 10W each (140w total).

    Q. So, what happen if we run the leds with less watts? They have less Lm?

    Q. And what is the symptom if run with less Amps? (on the cree xml website says that holds up 3amps).

    If you can reply, I appreciate it, I’m confused by this!

  2. keno Says:
    December 30th, 2012 at 2:10 pm

    To answer your questions:

    Q. So, what happen if we run the leds with less watts? They have less Lm?
    Yes at a lower current level, the LED’s will have less lumens. The LED’s will turn on at around 350ma of current.

    You can see the lumens range on this page at the CREE website: http://pct.cree.com/register.asp

    Q. And what is the symptom if run with less Amps? (on the cree xml website says that holds up 3amps).

    If you run the LED’s at a lower current range, the LED’s will run cooler. The LED’s can run at a maximum of 3A. Just because they can run that high, you don’t have to run them at the maximum. For the plants I am growing, I have found that I don’t need to run them that high. I would suggest getting a PAR meter and adjusting your light output to match the plants you are growing.

    I hope this helps…..

  3. Sharky Says:
    January 29th, 2013 at 4:24 am

    Hello Keno,

    First of all great work on the articles they are really useful.

    I hope you will have time to help me with my LED dyi project. I have a 55 gallon 40x20x20 inches aquarium. I am going to use 50% T3 Cree and 50% T6 Cree leds. For my tank dimensions how many leds do you recommend 10, 12 or 14 ? Also how do i align them on the heat sink in a straight line or zig-zag and would a 1400mA be a good controller to use or do i need more Amps.

  4. Jonathan Says:
    April 7th, 2013 at 1:35 am

    Would you ever consider doing commission work? In other words, if someone were to buy the supplies and get them to you, would you be able to put it all together for a fee? Your DIY build looks to be one of the nicest, most economical out there…