Daylight/moonlight Two-way LED Fishtank Light




Introduction: Daylight/moonlight Two-way LED Fishtank Light

My wife wanted a new fish-tank for Christmas, so I decided to make a two way light for it using white and blue LED's. I made a LED light bar out of aluminum and a power supply for it.

Step 1: LED Light Bar

I wired 5 blue LED's in with the white ones as the blue light really brings out the color in the fish. The 10 other blue lights are wired separately as a "moonlight" effect.
Make sure that your soldering iron is not set too hot, or you can burn up your LED's (I fried 3 before i realized what was happening)


46" long aluminum bar with a channel down the middle of it
20 white super-bright straw hat LED's
15 bright blue LED's
22 gauge wire, I used yellow blue and black
about 5ft of 3 conductor cable(shielded)
4 pin molex connecter with back-shell and pins
PVC heat shrink
super glue
potting compound

center punch
drill bits (various sizes)
countersink drill bit
orange sticks
razer blade(exacto knife will also work)
heat gun
wire strippers
crimp tool (for molex connector)
soldering iron (with solder and flux)
masking tape
bench vise (not required but it is handy)
cutting fluid (also not required but it allows you to cut a cleaner hole)

Step 2: Drill Holes

I measure and mark my holes, starting with the larger holes for the straw hat LED's. Use a hammer and center punch then drill small holes (I find it is very handy to start your holes small first then use the larger bit, so that the large bit doesn't "wander"). Use the counter sink bit to clean out any burrs. I then measure and mark out the smaller holes for the blue LED's. Center punch and drill them as before. Don't forget to De-burr. The bar can be cleaned if with a rag and a little isopropyl alcohol.

Step 3: Adding LED's

I use a small plastic cap, and a little super glue. I put the superglue on using a small piece of metal wire. Use a orange stick to seat the LED's in place. Make sure that all the LED's are facing the same way (the order of the component leads are long, short, long, short....continued for all LED's)

Step 4: Wire LED's

I use yellow wire for the "daylight" circuit, and blue wire for the "moonlight" circuit. Wire the LED's anode to cathode in a chain skipping the 2 outer blue LED's per LED group. I then use black wire at the end of each chain for my ground connection. After wiring the white and blue chain, I wire the blue only chain. I then strip and dress my cable. I use the white conductor for daylight and red for my moonlight. Black is still negative. After soldering the cable in and covering the solder joint with heat-shrink I superglue the cable down into the channel. I also superglue the shield to the aluminum channel( I will connect this to my earth ground connection later in the power supply.) I then strip, dress and build up the molex connector. I use a rubber bushing under the back-shell for waterproofing.

Step 5: Potting Compound

First taped the ends to keep the compound from running out the ends(if you are not careful this stuff will get everywhere). Make sure the channel is level and on a stable surface. I use a small plastic cup to mix it up(mix well). Carefully pour the compound into the channel, covering all wires and components. I use a orange stick to push down any wires that try to rise out. The potting compound will take a long time to cure, and "baking" it helps it along. Since I don't have an oven large enough, and I didn't want to try to move it once the compound was in, I used a heat gun to speed up the curing. About once an hour for about 6 hours I used the heat gun to get the whole thing good and hot. After letting it set overnight, it was fully cured. This creates a hard "rubber" like material that is waterproof(important for a fish tank). I then used a razer blade to carefully scrape of any excess compound that ran down the sides.

Step 6: Power Supply

I made my own power supply useing a bridge rectifier and a few simple components.

Basic metal handy box
bulkhead connector
two position switch
re-purposed power cord
7 grey wago terminal blocks(with 1 end cover)
1 green/yellow wago terminal for ground
short piece of din rail
3 10-32 screws(2 short and 1 long)
3 10-32 keeps nuts
electrical components as indicated on schematic
4 4-40 screws and 4 4-40 pem nuts
molex receptical with 4 pins
black and white wires for AC
blue and green wires for DC
green/yellow wire for ground

I used the handy box as the case because it was cheap. I mounted the din rail with the 2 short screws and 2 nuts using existing holes. I opened 2 knockout holes in the side for the main power and the dc power to the LED's. I had to drill 4 small holes for the molex connector and install the pem nuts on the connector. I expanded an existing hole in the side for the switch. I mounted the bridge rectifier with the long 10-32 screw using another existing hole. I then put in the wago terminals. I cover all components with heat shrink to prevent shorting. Then I wired to the schematic. I used a green/yellow wire to connect the shield connection from the cable to the protected ground from the main power cord. The pin-out I used for the molex connector is: pin 1 day circuit, pin 2 moon circuit, pin 3 negative, pin 4 ground.

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    7 years ago on Introduction

    My wife got some new decorations, so I updated the pictures. Enjoy :)