Fish Tank LED Moonlight / Moonlighting





Introduction: Fish Tank LED Moonlight / Moonlighting

This instructable will show you how to safely add LED lighting to a fishtank/vivarium.

I've tried previous versions of night / moon lighting in the tank, but none were up to the task:

Moonlight v1 - waterproofed high power LED's attached to the side of the tank - these gave pretty good lighting but there were too many pools of light in the tank, and also the number of wires was pretty unsightly.

Moonlight v2 - Cold cathode lighting (from a PC mod kit) , however as Ive got a large tank (180ltr) and I needed to extend the wires from the cathode tubes to the inverter - however when I did this I found that they no longer worked anywhere near as well (it seems this is a known issue with cathode lights).

So....back to Maplin and moonlights v3 is here!

If you want to see the tank please take a look at Fish Cam where there are 2 streaming live cams! To see how I did this you can view my other instructable HERE.

Step 1: Be Safe!

Before adding any more electrical stuff to your fish tank please, please install a RCD (Residual Current Detector) onto the power supply, these cost about £10/$20 and will save your life!

Water + Electricity dont make happy fun!

If the choice is dead fish or dead people, i know what I'd choose.

Admittedly Ive got a bit more under my fish tank than most (2 Cameras, Firewall, Router, Wireless gateway, 2 Web cams, 2 timers and more.!) but this is a worthwhile investment!

Step 2: The Bits You Will Need (and Maybe Some More!)

What you will need:
1 x 12v power supply (or whatever the LEDs need)
1 (or 2) x Strips of LEDs (or alternatives)
1 x Glue gun
2 x male phono plugs (if installing 2 strips)
2 x female phono plugs (if installing 2 strips)
1 x patience!
1M dual core wire

I decided to use the phono leads as detachable power leads for the lights so I can remove them from the tank easily when cleaning.

nb:/ If you cant get the LED strips then this would easily be achievable using a bunch of leds on a piece of stripboard.

Step 3: Solder on the Wire

Locate the +ive and -ive terminal on the LED strips, and solder on the wire.

Step 4: Measure Where You Want to Install the Strip on Your Tank

Open up the lid on your tank and measure from the strip light to the edge of the tank, then use this measurement to choose where to install the stip on the lid.

Step 5: Water Seal the Connections and Glue to the Tank Lid

Use the glue gun to totally cover the solder joint, and then use it to glue the strip to the fish tank lid.

Step 6: Waterproof the Stip

The LED strip i bought was not waterproof and was meant to be used in a dry environment, to make it 'fish tank proof' I used the glue gun and covered it from top to bottom in glue!

Step 7: Connect the Phono Plug and Trunk the Wiring

Now solder on the phono plug and use cable clips to hold the cable in place.

Step 8: Almost Completed....... well kind of!

After installing the one light i decided it didnt light quiet enough so I installed another strip onto the other lid on the tank!

Step 9: Connect Both Stips Together

To make both strips of LEDs work at the same time I installed a joining block with both female phono plugs coming off it - so that everything could be ran from the same power block.

Step 10: The End Result

Voila! Here is the end result - note the photo of the LEDs in position after a night covered in water (the glue'ing is definately needed!).

Dont forget to take a look at the fish tank Fish Cam!

Please post any pics if you give it a go!



    • Water Contest

      Water Contest
    • Stick It! Contest

      Stick It! Contest
    • Creative Misuse Contest

      Creative Misuse Contest

    27 Discussions

    Very nice it looks fantastic at night. This is something I will be doing in the future. Thanks very much.

    Sadly I havent measured the usage, but its certainly low, and 100% way way lower than the heater in the tank!

    Very nice looking results. I commend you on this. I've been planning on doing something like this in my snake's terrarium, hopefully mine will look somewhat as cool as yours.

    2 replies

    hey does anyone know where i can get an LED strip online??? ive been searching for a while and cannot find anything long enough for my 4ft long tank

    It`s really nice the way you plan it with those phono connection
    i was searchin 4 a way 2 do it
    for 3 aquariums it`s 2 nice
    keep the good job

    ahhh so you live in England. well i live in Newport Vermont. and i am setting up a 30 gallon tank i think. (that is 25 uk gallons to you) i just use a purple florescent fish tank lamp witch seems to be suitable. soon i will be setting up a salt water tank.

    I did exactly the same except i used cold cathode tubes (blue ofcourse). i find they are brighter than LED's, i used them in my cars footwells, and with a 12v transformer, they workd indoors. il post up a picture of my tank soon, 2 tubes makes the tank look stunning. and i think the fish like it. greatt instructablee!!!!

    I had a blue cold cathode light from my old computer. Since my aquarium has a dry area for the lamp, I stuffed the light in there with the fluorescent tube. Also, I put a piece of cardboard and tissue paper around bulb to darken it closer to moon light brightness... looks cool. i have a cloudy water problem at the it glows.


    I love your tank. This is a great instructable. I have a 75 Gal tank and I am using a cold cathode setup for my moonlights. My tank is only 4 feet long so they worked good for my setup. I use two plug-in appliance timers. My moonlights come on 30 minutes before my fluorescents turn off. Then my fluorescents come on in the day 30 minutes before my my moonlights turn off. I run the moon lights for a few hours at night, then total darkness, then moonlight for about an hour in the late morning, then fluorescents for a good chunk of the day.

    Works a treat, thanks! I added a little potentiometer right after the adaptor, in order to dim the light to just the right setting. Yes, nice one!

    2 replies

    Yep, this is one with both lights on, the fluorescent daytime light and the LED lights. I used two strips of 15 LEDs.

    The dimmer control - which was really easy to add on the main cable going to the lights - is great, as it allows you to look for a really comfortable light level for you and the fishies.

    I'll try and get one with just the LEDs on, but it's hard in total darkness to get a good shot. I'll try with some background room light, like you did in your rather nice pics!

    Slightly higher res image here.


    Nice instructable, clean job. I love this effect. but I'm worried about something; all the leds flashlights and lamps, advice that you shouldn't point them at the eyes. I see my fishs as more delicate creatures. Maybe this can get their stress up and get then prone to get sick. Or I'm just talking nonsense, and it doesn't do anything to them? (mine is:53L fish tank 9 zebrafish 6 guppys and 1 cory)

    3 replies

    Hiya, I see your thoughts but in all honesty I dont think this is an issue. As the LED's are all above the waterline the light gets heavily diffused by the water so the fish cant directly see into the LEDs. Also they are significantly less bright than the overhead strip lights which are on all day!

    you dont get as much algee if you dont leave it on all day the light coming in the room is enough

    If you live in a house with lots of light..... but if you live in a terraced house built 105 years ago in London and the tank is in the corner then you need the lights, as I do! I get no algee.

    Is a vivarium a virtual aquarium? In any case, good idea and awesome fish tank!