Picture of LED Aquarium Moonlights
I have had my 55 gallon aquarium for half a year now and wondered "what do my fish do after the main lights go off?"  I began searching the internet and came across the idea of using dim blue light to simulate 'moon lighting'.  After I took a closer look and dug deeper on the web, I discovered that they were just blue LED's.  Simple enough I thought.  That led me to begin designing my own.  This instructable focuses on the 'kit' style hoods.  If you have a different style, you will have to find a different way to mount the LED's.

Make sure that you read through the entire instructable before you start.

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Step 1: Planning

Once you have decided to build these lights, you must decide how many LED's and which ones you will use.  I went with 8 LED's, 4 in each hood and it turned out perfect.  Determine which LED's you will be using and what your power source will be.  The LED's I used were rated for 2.8V@20mA.  My power source was an old wall wart that was rated for 6VDC@100mA.  Make sure to actually test the voltage coming out of the supply as mine was up at 9.9V!  Don't forget that when you work with LED's you need to limit the current by using resistors in the circuit.  You could do all the math, but being lazy, I used this site and it worked awesome, just plug in your numbers and it does the rest.

Now you have to determine how to mount the LED's.  I simply drilled holes for the LED's in the existing fluorescent mount, however your hood may differ.

Step 2: Materials/ Supplies

Picture of Materials/ Supplies
LED's - blue in color
Wire - small gauge
Power supply (old transformer)

Soldering Gun/Iron
Glue gun
Glue sticks
Drill Bits

Heat shrink tubing
Heat gun
Helping Hands

Step 3: Dismantle Existing Hood

Picture of Dismantle Existing Hood
Pretty self explanatory, just take out the bulb, and undo the screws to remove the white reflector.  Don't harm the existing wiring or hardware.
poelinca2 years ago
What most people use are blue LED's, but the color temperature of the actual moonlight might be different ( depending on LES's ). Moonlight color temperature is 4100-4150k . For more info on how we see it and how it actualy is checkout this post

p.s. i plan to follow this instructable, but i'll get different kinds of lds
manlyfish5 years ago
what type of fish do you have?

Willard2.0 (author)  manlyfish5 years ago
3 Tinfoil Barbs
3 Clown Loaches
7 Tiger Barbs
1 Red Tail Shark
cool i have
-2 corys
-1 rainbow shark
-1 ballon molly
-1 female betta
-1 lionfish
This turned out really good!
You might have been able to get away with using only 4 leds if you used wider angle ones like 120 degrees
Willard2.0 (author)  OverSaltedFry5 years ago
I probably could have, but these were the ones I had on hand.  The wider one's would be better, because they would make a broad glow, instead of the circles of light that I currently have.