Here’s how you can build your own high-powered grow lights at a fraction of the cost!

When I first started messing around with the concept of an indoor aquaponics system, it began more as an experiment than anything else. To be honest, I was mostly interested in reducing the amount of water-changes I would have to do in my 130 gallon freshwater tank. I started with a couple racks of Gro|Dan that I pumped water from my tank into via a manifold / drip system, which then drained back into my freshwater system for the fish.

At the time, I didn’t worry too much about lighting. I had a spare UV light from my Saltwater tank which worked fine to grow corals, so I figured I could just use that. Ultimately, I bought a couple more cheap $10 dollar fluorescent fixtures as well. I mounted all of them haphazardly to the ceiling beams in my basement, turned on the pump, and let it run!

For the most part the system actually worked. By the time I tore it all down I had a parsley plant the size of a small tree, some basil, and a few other various herbs — and fewer water changes for my tank.

A few months later, when I decided to get serious about building a real indoor aquaponics garden I took a fresh look at everything I was doing and figured out how to do it better. One big concern to address was lighting. First, I was going to need a lot more of it — I was planning on setting up 4 grow beds and each was going to need it’s own lighting. Secondly the lights themselves were going to have to be much more intense. In other words, I was going to need to replace my $10 cheap fluorescent fixtures with at least 4 high-powered larger light fixtures.

High powered fixtures meant significantly higher electric bills, not to mention each one could cost hundreds of dollars each. So, I decided to build my own – and here’s how I did it!

Building DIY Grow Lights

What you’ll need (per light)

24" Section Heating Ductwork	x1
Threaded Zinc Rod	x2
Snap-In Porcelain Light Fixtures	x3
Common Extension Cord	x1
Wire splitters / Electrical Tape	x1
Female Electrical Plug End	x1
Screw-In Grown Bulbs	x3

To get started I decided to use 24″ inch sections of heating ductwork you can pick up at Home Depot for about $3.50 each. These metal ducts are designed to spread open and then lock in place to ease installation, which makes them perfect for what I wanted to do. The idea was to hold them open using metal rods and use them as the primary structural feature / reflective surface of my grow lamps. To accomplish this, I bought a couple of threaded zinc rods that I could cut down to the roughly one-foot length I needed with a hack-saw and bolts to match. Using a drill with a metal bit and a couple of clamps I drilled holes 1/4″ off of each edge of the 24″ section of duct work, then carefully spread each open and slipped the one-foot threaded rod in to hold the duct open.

Be very careful when working with the ducts. The edges of the metal are very sharp, almost knife-like. I made the mistake of being careless and ended up almost having to go to the ER for stitches when I sliced my finger open badly. The first thing you should do once you have gotten the duct spread open is cover the edges in something like duct-tape to prevent injury.

Once the duct had been transformed into a reflective dish and basis for my fixture, it was time to add the light fixtures themselves. I decided to install three light sockets per fixture, so I picked up 12 of these snap-ins for about $3 bucks each. These were ideal fixtures for two reasons. Since they were snap-in all I had to do was drill the appropriate sized hole in the duct to install them, and I wanted to make sure they were made out of porcelain as well in case they got hot.

With the fixtures installed all that was left to do was wiring. In my design, each light fixture can be powered by the fixture next to it and chained-together. So for the wiring of each fixture I cannibalized some garden-variety extension cords I had laying around the house (if you need some I used something like these) by cutting off the female adapter side to about 3 feet long and replacing it with a single female plug. Using some tap splices, I attached each socket to the extension code and then carefully taped each up with some electrical tape for good measure.

To wrap everything up, I pulled out the duct-tape again and used some to secure the power wires to the top of the fixture, and installed eye-hooks and chains to each so I could hang them as necessary. Viola! Light Fixtures for my aquaponics system!

Now that I had fixtures, I had to decide what kind of lights I was going to use in them. There are a lot of options out there for aquaponics light bulbs. There are standard incandescent bulbs, CFL bulbs, etc. If you want, you could install a light-socket splitter and run 6 grow-light CFL bulbs per fixture (for example). The important things to consider when choosing your bulb are:

• Wattage (how much electricity does the bulb consume)
• Lumens (how bright is the bulb)
• Light Wavelength / Temperature

The trick here is to find the light bulbs that produce the highest number of lumens with the lowest wattage in the correct wavelengths. When it comes to growing things, plants need (annoyingly) light temperatures at the lower and higher end of the visible spectrum and almost nothing in the middle (spoiler: most normal light bulbs are right in the middle temperature wise). What wavelengths / temperature produced by a light bulb is measured in Kelvins and can be found either on the packaging or bulb itself. For plants, you need both 3,000K and 6000K+ light, which means you either need to buy multiple types of bulbs (for example, two 6,000K+ and one 3,000K per fixture) or you need a bulb that produces both.

Rather than buying multiple types of bulbs, I personally opted for a single bulb that provided all the light I needed by using these LED grow-bulbs in my fixtures. They are a little pricey, but what I spent up front for each bulb I am sure to make back in electricity costs later.  They are extremely bright (almost blinding), provide exactly the correct temperature light, and best of all they aren’t power-hungry. When I was setting my system up, I bought the bulbs slowly over time as I needed them (started with only two bulbs per fixture, added a third when the plants started really going) which also helps spread out the cost a bit. As you can see from the picture below, the plants love them as much as I do!

Overall per fixture, with lights, I was able to keep the cost to roughly $75 dollars each in the end. If you like me want to spread the cost out over time, you could build one for as little as $40 dollars with a single bulb, and then add additional bulbs as your plants require it.

I hope you’ve found this useful, and if there is anything I’ve missed you are curious about please let me know.

In my next article on my aquaponics system, we’ll be looking at the grow beds in detail, so check it out!

Until next time!