Here I will walk you though the process to make true replacement LED lighting suitable for plants. I see there are many instructables about DIY LED lights, but most are not sufficient to grow plants! Based on the notion that you should have at least 1W of light per gallon, I have made this 18W system for my 12 gallon tank (12W of White light and 6W of Blue). I have also opted for the slightly more expensive route, an LED controller that allows automated daylight mode...but compared to typical systems sold for aquariums, mine is much much cheaper!
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Step 1: Acquiring Resources
Drill and drill bits
Coping saw (need thin removable blade)
Metal cutting hand saw
For this project, I used 1/4" wide aluminum U-channel for the heatsink available at your local hardware store. You will see the importance of this momentarily. http://goo.gl/cUX9iG This one is close, roughly $5.
For the hookup wires, I used old USB cables I had lying around, I just lopped off the ends and TA DA, waterproof power cables. Any will do, $0-3.
A standard tube of silicone for sealing the new fixtures (I used white). ~$0-4 at Lowe's.
Some sort of adhesive to attach LEDs to U-channel (I used gel superglue). $0-1 dollar store. EDIT: WARNING! while this worked fine in this project, the next time I tried to use super glue to attach LEDs it failed...bad. So I suggest getting thermal epoxy that is waterproof. (such as arctic silver or similar) I got lucky the first time...but paid for my shortcut the next time...
Self tapping metal screws for attaching heatsinks to hood. $0-2 at Lowe's.
12v power source. I had a small PC supply so it was free. $0-15.
Now the fun stuff:
(12) 1w warm white LEDs (cool white is better) ~100lm /ea. Check DX.com, all sorts of LEDs for super cheap, these: 20 for ~$5. These are very powerful LEDs and need to be on a heatsink (Al U-channel)
(6) 1w blue LEDs. DX.com, I think I got 10 for ~$4
(6) 8.1ohm 1w resistors. http://goo.gl/9sYeKR Amazon 200 for ~$9
(1) Niceeshop LED control module: 5CH, 20A total. http://goo.gl/HDMBn8 Amazon for ~$32 VERY MUCH WORTH $32!
Total cost plus extras for the next project: $56-80
The controller can be left out of this project, and it makes it much cheaper, but I wanted the automatic lighting and the daylight sequence. This works fantastically by the way, and is extremely easy to program! This is also way overkill for such a small setup, but is easily expandable.
Step 2: Cutting Hood and Placing Al Heatsinks
Start by figuring out where you want the LEDs in the hood and determine how long you want each segment. I went with 3 segments, (2) white, and (1) blue. NOT SHOWN: I cut them all to about 8" and attached 6 LEDs per segment. I used superglue to attach each LED, it actually works great at conducting the heat away from the diodes. Be sure to attach and solder the LEDs in sets of 3, Three LEDs in series plus the 8 ohm resistor will give the correct current and voltage across each LED.
Next, drill holes in the the hood at the ends of each segment, be sure to go smaller, In my case, I cut ~6" holes so I could attach the U-channel using the self tapping screws.
Once the holes are drilled, take apart the coping saw so you can place the blade through one hole and, after attaching the blade again, cut all the way to the next hole. As you can see, my cuts were a little rough, I wish i had a proper work space...But I managed.
Once all the slots are cut, I smoothed the edges a bit with a knife, then attached each using the self-tapping screws.
Step 3: Wire Each Segment
I chose to make two white channels and one blue channel. I wired the two inner most sets of white LEDs as the first channel, and the outermost as the second channel. Again, I used spare USB cables, each as 4 conductors plus a common, for ease of wiring, I just used 3 cables and left the common floating. The pictures are a little hard to see, but this is a very basic circuit.
When all the wires are soldered on, and you have finalized cable routing, its time to seal it all up! I used standard bathroom silicone caulk and aside from not using clear, it worked just fine. Just make sure you get all the wires and bare contacts well sealed to prevent rust and corrosion. I also added some tape to the topside to prevent caulk from oozing out of the channel since my cutting was imprecise, see last picture.
Step 4: Testing and Final Steps
Before I sealed everything I did check to ensure all LEDs were still working, and they were! From there, I just had to program the controller.
I setup the program to come on at about 6:30 AM at very low intensity, and slowly ramp up until about 9AM, then it gets faster until full brightness at noon, then declines throughout the evening and after 7PM Blue 'moon lighting' takes over. This looks great, I'm still tweaking the actual program though, eventually I may make a new instructable on programming it for just such an application.
As you can see, there is some light leak from the top, but overall its not too bad. My fish and plants have been doing very well. The heatsinks get a bit hotter than I'd like at 100%, but its still less than their critical level. If I remade this I might use a larger spacing between LEDs, or just buy a larger Al channel.
In other news, I have recently purchased a bigger aquarium, 60 gallons! I'm still working on all the custom stuff I'm doing to it, but stay tuned for more on that project in the coming weeks!
Things to come:
Reenforced MDF tank stand.
Custom over-tank filter good for ~140 gallon tank (660GPH!).
Custom hoods with total white LED output of 72W plus accent blue and red lighting (and you guessed it, the Niceeshop LED controller).
A better, more uniform black aquarium background.
Automatic water level maintainer.