Using waterproof LED strips to light up some fishy goings-on.

I have a 190 litre Juwel Trigon aquarium which, when purchased in 2009, came equipped with T5 fluorescent lighting. To be honest, it works just fine, however the lighting is a sealed unit to keep the water out and the two fluorescent tubes are connected in series so when one tube burns out, nether tube will light.


That's a problem because I use two different tubes, one is a white "daylight" tube, the other a blue "marine" tube. Because they're a non-standard size so Juwel can prevent you from sticking just any old fluorescent lamp in there, determining which has failed and what kind of replacement one needs to now purchase becomes something of a pain in the hat.

Added to that, running two 28W tubes plus the ballast to drive them makes for around 60W of consumption on the lighting, plus it gives off heat which is a problem in the summer when the water temperature is already a bit toasty for my tank dwellers, and all this gubbins makes for some high voltage hovering just above the waterline which is fine so long as that enclosed lighting unit remains enclosed and no water finds a way in.

Anyway, to cut a long story short, although my T5 unit is still running smoothly, a friend of mine who has the older T8 lighting in his Trigon tank called me recently to say his lights had failed. Replacing the tubes didn't cure it and there was nothing wrong with the fuse, switch or wiring, so a blown ballast was the likely culprit.

A bit of sleuthing on the 'net found this to be a common problem, and the only real suggested fix is to fork out around a ton on a new lighting module from Juwel. I had other ideas though, so let's take a look at a new way of lighting an old tank that should cost less, be cheaper to run and last longer....

Firstly, here is the T8 lighting module in question. I point out here that my pal Steve has already mauled this thing open with the aid of a drill and chisel. As a sealed unit it wasn't made to be taken apart, so he drilled a hole in one corner, stuck in a chisel and peeled the upper layer off the module to reveal the ballast and wiring within.

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And here we can see that failed ballast...

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I could fit a new ballast easily enough, and I had compatible models on the shelf, but now that the unit has been broken open, I'm unlikely to ever be able to get it satisfactorily sealed back up again after I make repairs. Fluorescent ballasts also get quite hot, so my non-Jewel replacement may not be suitable to be mounted inside an enclosed plastic unit, and any kind of waterproofing I apply such as silicon or gels may be affected by the heat, the humidity or may cause fish-unfriendly pollutants to leak into the water.

The bottom line is that I can't effect a satisfactory repair using fluorescent technology because I cannot guarantee to keep that ballast or any of the AC/fluorescent wiring away from moisture, and I don't want to see Steve or his fish get fried through any botched repair of mine.

With that in mind, the fluorescent and any idea of AC above the waterline was ditched entirely. Instead, I'm going to stick some 12V waterproof LED tape to the body of the lighting unit.

I've used this stuff on numerous projects, especially undercupboard kitchen lighting. It tends to comes in five metre reels, can be sourced in all colours including colour changing, can be single or double density (300 or 600 LEDs), and can come in waterproof or non waterproof flavours. Cut points every few centimetres allow it to be trimmed to size and for wires to be soldered on. I used the same sort of stuff in my office lighting project a few weeks ago.

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The waterproof variant comes encased in a gel-like coating which can be sliced off around the solder points by a Stanley knife. A solid 3M adhesive backing means it can be stuck semi-permanently almost anywhere and I've even stuck it on wooden sleepers outdoors where it has remained steadfast.

For this project, I have sourced strips in warm white, natural white and blue, the first being the single density (300 LED) type and the others in the double density (600 LED) variant. These strips have been cut to match the size of the lighting enclosure and are adhered to the sides and underside. Six strips, three of each colour and each about 60cm long, have been fitted.

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Why the mix of colours? Well, during prototyping I found warm white made the aquarium look yellow, natural white was too stark and blue helps bring out the colours of the tropical fish. When mixed together it forms quite a nice balance.

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Aquarium sealant was used to cover over the solder points and the supply cables to the strips were joined within the enclosure then sealed up. It's a lot easier to seal up a positive/negative 12V DC connection than to try to keep both the AC connection and a fluorescent ballast dry, and the constant voltage driver to run these strips will be located in the cabinet under the tank well away from any wet bits.

I've also installed a two gang light switch in the cabinet on the DC side of the driver which allows the white LED strips to be controlled separately from the blue as per the schematic below.

This means the tank can be illuminated using one of three effects...

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Above: white only, gives a warm glow.

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Above: white and blue, a more natural, fresher light.

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Above: blue only, might be used at night as a "moonlight" effect.

In theory, this solution should offer longer life over fluorescent and cost less to operate. It also allows for customisation of the lighting effects, doesn't give off any waste heat and removes the need for high voltage components housed just above the waterline. It is very important however that you buy the right kind of waterproof LED lighting. There are different scales of 'waterproof' with IP67 LED strips only designed to be immersed in water for a short time while those rated at IP68 can supposedly be immersed indefinately.

Although we're not immersing the strips, they are in a very humid environment and IP67 isn't going to cut the mustard as I can demonstrate....

For the original prototype my usual suppliers didn't have the IP68 strips immediately available so I used IP67 strips. After just ten days, they looked like this...

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Ouch! Despite being waterproof to IP67 and not immersed in the water, just located in the humid environment above it, water has nonetheless penetrated both the white and blue strips at multiple points causing discolouration of the protective gel, shorting out of the resistors and complete or partial failure of individual LED elements as they become subject to over-voltage.

The IP68 rated strips which should be more suitable for this project come fully encased in a gel-filled outer plastic enclosure and are both thicker and heavier than their IP67 counterparts.


They also have end caps for placing over cut points or where wires have been soldered into place. Aquarium sealent used in conjunction with the end caps should ensure a suitable seal.


Personally, I believe it would make sense for the likes of Juwel to be switching to this kind of technology, but I suppose as long as they can sell non-standard replacement fluorescent tubes then they won't be looking to change their manufacturing process any time soon. If your Juwel lighting has failed and you're handy with a soldering iron, installing good quality IP68 LED strips can cost half as much as a new lighting unit and be cheaper to run.

That said, like any other project listed on this site, any attempt to replicate it is at your own risk and I advise against playing with any kind of electricity if you feel you're not comfortable or competent to do so! [Disclaimer]

Update 01/08/16

I've just had to shell out for a new Juwel T5 fluorescent unit as my super LED solution has died. Well, actually it didn't die outright, but over the last few months sections of the IP68 LED strips had begun to fail.

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It was slow at first, but recently the failures seem to have escalated leaving the tank much darker. The blue strips, while still working, also seem duller than they originally used to be.

The wierd thing is that it does not seem like moisture has got in, so the IP68 rating is intact, and there is no sign of anything outwardly being wrong, yet whole sections just aren't lighting.

The way these strips tend to work is that three LEDs each rated at 3V or so are connected in series with a resistor of somewhere between 150 to 180 Ohm, so a failure of any of these elements or of one of their solder joints will see a section of three LEDs die out.

As it doesn't appear to be moisture related, I assume it's just failed because these LED strips are cheap Chinese no-brand shite which is highly likely as the supplier I bought them from at the time subsequently had a high failure rate across all their products resulting in my kicking them out of bed a year or so ago.

Maybe I could resurrect the idea by using new strips from a reliable manufacturer, but sometimes the path of least resistance is just to buy the thing that was made for the job and be bloody well done with it.