DIY Moonlights

DIY Moonlighting / low level lighting
Written by Smithrc

For all of us out there that love our plecs - we've know that we have taken on fish that we know we wont see all that often...

However, at night Plecs come alive and low lighting is a great way to watch them without disturbing their activity.

This little project should take about 30 mins to fit to any tank and cost about £10 - but it will cost you hours at night as you sit and watch your plecs go about their business in the subtle lighting.

First off you'll need....

1 - A cold cathode set (Blue for moonlights or white for ambient lighting - your choice )
Have a look on eBay for 'Cold cathode' they are popular for PC case lighting and are ideal for the moonlight application as they come in an acrylic tube that will keep them dry.

2 - Next you need a power supply
A good quality variable voltage AC/DC adapter 3-12v 500ma - if not then something that gives off 5-6V and 300ma or more will do nicely (old nokia phone charger laying about??)

3. Wire strippers and tape (or soldering iron if your going to do it properly)

4. Your choice of cable ties, sticky pads or Velcro cable tidies (depends on how your going to fit them)


There are a few thing you need to consider before setting out.
1. locate the driver unit somewhere dry (not under the hood due to condensation)
2. will the wire to the tubes reach the driver unit location?
3. will the power supply reach the driver unit?

Once you have planned that its time to start wiring.

The cold cathode kits are usually designed to wire into the power connector of a PC so cut the connector off. The black will be ground and the yellow wire is therefore the positive. normally this would be 0V and +12V. So you need to work out which is the +ve and the -ve on the supply and wire them up.

If your doing this in a permanent fashion, solder the wires together. If, like me, you don't like the thought of not being able to use the adapter for anything else, ever again, try the "bodge and tape" method

yellow = +
black = -

That's the wiring out the way...


Unless you want to start messing about lengthening the wires to the tubes, you need to be able to locate the driver circuit outside the tank in a position that the wires will reach to the tubes. (if you do decide to lengthen them - lengthen them both equally or you'll end up with one dimmer than the other - speaker wire works by the way)

We have them fitted to most of our tanks. here is how we have fitted them to a Tropiquarium 88 to get your own ideas flowing. These tanks have a hard plastic condensation tray that we have fitted the tubes to with the sticky foam pads.

Then drilled a hole through to the gap in the back of the lid, passed the wires through, put the screen back on and I put the driver unit and switch in the covered area at the back.

HOWEVER, that isn't that easy on most tanks, I have however come up with a great method of fitting these that will work with ANY tank....

Velcro cable tidies!! - the strips of double sided velcro for tidying up cables...

because I'm cheap, I cut them up along their length and cut into sections that are slightly longer than I need (so you have a good overlap)

Then simply hold the neon tube in place at the side of your normal light tube, flex the acrylic tube SLIGHTLY in the middle and wrap two bits of velcro round it - then slide one towards each end (don't flex it too much or you'll break the neon in the centre)

No chance of them dropping off and if you've flexed it right it wont move round the light either.

Here is them fitted to our Juwel Rio 240.

Setting the voltage.

I've recommended about 6V as this should mean that its not too bright.
you may find that your tank needs the voltage up higher to light it properly, just make sure that the rest of your fish still sleep. If they still swim around like the do during the day and don't loose their colour and sit floating then its too bright and you need to turn the voltage down a bit.

Your eyes will adjust to the low light pretty well, so just sit in the room with the lights out for 5 - 10 mins and you should be able to see a lot better.

And here is the bit that should convince you that its worth doing, and that 12V is too bright

(NB. taking pictures of moonlit tanks is hit and miss unless you know what your doing... shutter speeds made all the difference to how bright they look in the pictures... so results will vary)

4.5V (these are with 2x 12" tubes over the trop88 - 33" long 130L)


and 12V

7.5V (this is 2x 12" White tubes over the Rio 240 (4ft long)