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How to Build a DIY LED Aquarium Light, Part III

Updated on July 14, 2012

Part III: Planning Your Array

In Part I, I told you about why you might want to build an array. In Part II, I talked about the parts you'll need and where you can buy them. In this article I'll tell you about how to research and plan your array.

My apologies up front: This is going to be a longer article. There's a lot of info to digest when you're planning an LED array; I researched mine for more than a year before I finally built it. It may take a little bit longer to read this article, but it's very important to have a firm plan before you start throwing money at an LED array.

There are many places you can go to research DIY LED projects. In addition to my guide, there is a wealth of information available elsewhere on the Internet. Many of the popular aquarium forums have very active Lighting forums. Most of them have many DIY LED build threads, from which you can take some ideas. After you've finished reading my articles, I definitely suggest looking at some of these sites for additional ideas.

When you're done researching, you should know the answers to the following questions:

  • Will I be soldering my array?

  • Which brand of LEDs will I be using?

  • How many LEDs will be in my array?

  • What colors of LEDs will I be using, and how many of each?

  • How will I lay out my LEDs on my heat sink?

  • Will I be screwing or gluing my LEDs to the heat sink?

  • What kind of driver(s) will I be using?

  • Will I be dimming my array, and if so, how?

  • How will I wire my array?

  • How will I protect my drivers?

  • How will I mount my array?

I'll discuss each of these questions and give you my own feelings on the subject.

Will I be soldering my array?

This one comes down to your own comfort level with soldering. At first I thought I wanted to go solderless. Solderless LEDs are plug-and-play and don't carry the risk of burning your house down. However, you lose a great deal of flexibility by using solderless LEDs. Solderless LEDs aren't available in as many colors, and are more difficult to use with optics. They also cost more.

Ultimately, I decided to solder my array. I wanted the flexibility to use any type of LEDs I wanted, and I was on a budget. However, you can still build a very good array by using solderless LEDs.

Which brand of LEDs will I be using?

There are really only two brands to choose between: Cree and Bridgelux. Cree LEDs are more powerful and more efficient, but are also two to three times as expensive. Bridgelux LEDs are perfectly serviceable for most applications, but they don't have the power to penetrate deeper tanks.

I went with Bridgelux for most of my LEDs. My tank is not overly deep, so I didn't need the extra power of Crees, and the lower cost of the Bridgelux LEDs let me put more LEDs onto my array.

How many LEDs will be in my array?

The answer to this question depends on three factors: the size of your tank, the strength of your LEDs, and the lighting needs of your tank's current or future inhabitants. If you want to have enough light to keep just about anything, aim for one LED for every 15 square inches of surface area in your tank.

If you'll be hanging the array very high above the tank or you have a deep tank, you may need to use more LEDs. If you have a very shallow tank or are certain that you will never want to keep light-hungry organisms, you can decrease the number of LEDs in your array.

I knew I wanted to be able to keep stony corals and clams, so I knew I needed at least 24 LEDs for my tank. I also wanted the flexibility to dim my lights, hang it high above my tank, or use the array on a deeper tank at some point. I ended up using a total of 33 LEDs.

What colors of LEDs will I be using, and how many of each type?

There are several colors of LEDs that are suitable for aquarium use. They are:

  • Royal Blue
  • Cool Blue
  • Cool White
  • Neutral White
  • Ultraviolet
  • Deep Red
  • Cyan
  • Turquoise

Royal Blue (455nm) and Neutral White (4500k) are the backbone of most arrays. You can construct an entire array using just these two colors, though some people choose to include other colors for aesthetic or photosynthetic purposes. Some corals benefit from the inclusion of ultraviolet light. Many of the other colors of LEDs are useful for bringing out different colors on your corals, which often get washed out in the traditional white/royal blue color combination.

A 2:1 ratio of Royal Blue:Neutral White tends to give the best color result. Mix in other colors sparingly. Some people recommend including one ultraviolet LED for every eight LEDs in your array. Lastly, a tightly clustered group of Deep Red, Turquoise, and Royal Blue LEDs provides a white light that still provides the rich colors of each individual LED.

I ended up using 12 Royal Blues, 10 Neutral Whites, 2 Cool Blues, 2 Deep Reds, 2 Turquoise, and 5 ultraviolet. I wanted a broad spectrum of colors for my light, and prefer a whiter look than many reefers do.

My final layout, to scale.
My final layout, to scale. | Source

How will I lay out my LEDs on my heat sink?

You want to lay your LEDs out so that they provide maximum coverage while still blending. If each LED is too far apart from its neighbors, you may cause a "spotlight" effect. You'll be able to see each individual LED's light beam, and your plants or corals may not receive the full spectrum of light they need.

There are many programs you can use to help plan a layout, from Google Sketch-Up to Adobe Photoshop to plain old Paint. If you work better with pen in hand, you can also draw a layout by hand.

Whatever you use, make sure you work with the proper scale. Your heat sink's measurements should be easy to find, but you might have trouble finding the size of your LEDs. I'll make it easy: Most LEDs are around 20mm in diameter, or .79 inches if you're metrically-challenged.

One advantage of using a program is that you can create objects that are exactly the size you need. If you are working with an exact scale model of your eventual array, you'll have a much better idea of what you'll do when the time comes to put it all together.

I used OpenOffice Draw to plan my layout. I set the size of my working area to the exact size of my heat sink, created a plethora of .79 inch circles, and drove my wife crazy for about a month as I painstakingly planned my array.

Will I be screwing or gluing my LEDs?

This is more a matter of personal preference. Gluing gives you more flexibility in where you place your LEDs on the heat sink, while screwing gives you the ability to easily remove and replace an LED. Drilling a heat sink can be a lot of work, and pre-drilled heat sinks are much more expensive.

I chose to glue my LEDs.

What brand of driver will I be using?

There are two reputable driver brands commonly sold: Meanwell and Inventronics. They each have their advantages and disadvantages, so it ultimately comes down to personal preference. Both are very reliable and fully capable of powering your array, so you can choose based on their features rather than their performance.

Meanwell drivers tend to be the most powerful, and they have an internal potentiometer that allows you to change the size of the current you're sending through your LEDs. These drivers can provide the extra power that Cree LEDs can really benefit from; if you're using Bridgelux LEDs you really won't be using these drivers to their fullest. However, Meanwell drivers need an external power supply to dim LEDs.

Inventronics drivers are a reliable driver. Unlike Meanwell drivers, Inventronics provide power at a static current. This can be both a positive and a negative; they tend to be more plug-and-play than Meanwell drivers, but they can't provide the extra power to really make Cree LEDs shine unless you buy one of the more expensive models. Inventronics drivers provide the power for dimming equipment, so you won't need an external power supply for dimming.

I chose to go with Inventronics for my drivers. I didn't want to have to mess around with the internal potentiometer; none of my LEDs could be driven at the higher currents of Meanwell drivers; and I didn't want to have to use an external power source to dim my LEDs.

Will I be dimming my array, and if so, how?

I would very strongly suggest that you include dimming in any LED array. You don't have to, but there are several advantages to doing so:

  • Light Acclimation. If you increase the amount of light in your tank suddenly, your corals or plants may get overwhelmed. A sudden "light shock" can harm or even kill your sensitive organisms
  • Color tuning. If you don't dim, you're stuck with the color that your blend of LEDs gives you. If you dim, you can fine-tune the color of your light by dimming each color of light on a separate channel.
  • Extend the life of your LEDs. Working at full strength makes an LED burn out sooner; if you don't need the intensity of your LED's full strength you can extend its life by running it at a lower power level.

There are two ways to dim your light: you can use potentiometers of some kind (sliding, knob-style, or something else), or you can use a reef controller such as the ReefKeeper. Potentiometers are cheap and easy to use, but they don't give you precise digital control like a good reef controller will.

If you have the money to spend, I would recommend a controller. There are many other benefits beyond just lighting control. If you do go that route, make sure you find out what type of dimming control it uses. There are two common types of dimming controls. One type is called 0-10v control, the other is called pulse width modulation. Both forms are effective, but they are not compatible with each other, so if you get a controller make sure that it uses the same type of dimming control as your drivers do.

I went the cheap and easy route and just used potentiometers.


How will I be wiring my array?

If you've constructed a scale drawing of your LED layout, this should be fairly simple to do. You need to connect your LEDs in series, positive to negative, starting and ending with the driver. Each driver has a minimum and maximum number of LEDs.

Each LED typically has three positive and three negative terminals that you can solder a connection to. Your goal in figuring out the wiring is to connect each circuit as needed without running a wire directly over the light-emitting section of your LED.

Typically, one side of an LED is lined with positive terminals and the other is lined with negative terminals. In some cases, you may have to rotate an LED when you mount it so that it faces the right way to accept a connection.

To the right you can one of my wiring diagrams. I adapted my earlier diagram, but removed the colors and drew lines to represent the wires. In an earlier draft, I also had the positive/negative terminals labeled. It took some time, but I was finally able to come up with a workable wiring layout.

How will I protect my drivers?

Drivers are sensitive electronic devices; if you keep them unprotected near a fish tank, evaporation or spills could damage them. There are several options. You can use very long wires, and mount the drivers well away from the tank. If you're mounting the LED array into a preexisting fixture, you can try to mount the drivers inside of it somehow. Last, you could store your drivers in a project box. A project box is small box designed for electronic projects.

Personally, I'm a fan of the project box. A project box will let you hide the jumble of wires your drivers will spew out by the time you're finished. You might have to use multiple project boxes, depending on how many drivers you end up using; I ended up using two project boxes.

My completed light hanger
My completed light hanger | Source

How will I mount my array?

This is a very important question to consider. Some options:

  • Gut a pre-existing lighting fixture and mount the array inside
  • Hang the array from your ceiling
  • Hang the array from a light hanger
  • Build legs onto your array
  • Build the array into a hood

Each of the options has their own pluses and minuses, which are fairly obvious. I was turning my aquarium topless, so I was planning to hang my array. I didn't have any fixtures to gut, so that wasn't an option. I live in an apartment, so I couldn't drill a hole in my ceiling. So, I built a light hanger for my array.

Final Thoughts

So, you've answered all of my questions. By now, a plan should be taking shape. You should have a pretty good idea of what you're going to do with your LED array.

One last caution before you actually go and build an array. Make sure you have some kind of splash guard for your LEDs. The actual light-emitting part of your LEDs is pretty small; if any kind of salt spray gets on the lens, that particular LED's output will be greatly diminished. In addition, salt spray can corrode the wiring connections.

So, now all that's left to do is to come up with your shopping list, based on your answers to my questions, order up the parts, and put it all together. Congratulations!


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