View Full Version : Underwater Fish Tank LED Lighting

02-04-2005, 04:41 AM
Looking to run some LEDs in a freshwater fish tank, driven by a Stamp to control lighting effects and timing.
The main electronics will be well away from the water, safely positioned with 3' wires running to the different LED units. Most of these will be on the hood of the aquarium, but I would like to submerge some also.
I will fully insulate the LEDs with RTV silicon and the project will be driven by a 12DC wall adapter.
If I were to have a failure in one of the leads carrying current to a submerged LED - what dangers are there to humans who may touch the water and to the fish in the tank? I will have a GFI receptacle, but think that it might be unnecessary based on having a 12 wall adapter that is basically an isolation transformer.
What thoughts do people have on this?

Brian Dalziel
02-04-2005, 06:50 AM
There should be no problem as this is all low voltage/current, yes?

For the fish there is no path to ground anyway, they are in a glass aquarium. It's the "bird on a wire" analogy.

For someone reaching into the tank, they create a path to ground through their feet or any part of the body touching earth. But again, as long as all is low volt/current there is no chance for danger.

02-04-2005, 06:59 AM
When you add water to a project that uses a·wall mount power supply·, it is best to use a GFI outlet.· This will take most of the danger out the project.


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02-04-2005, 08:02 AM
If you have a short between leads on the LED...I think you'll find your Wal-wart giving some added smoke F-X!!

Also, if you have a bubbler...I don't know if there's any metal bits that create a path back to a motor...who's case is probably a ground point....so your bubbler might quit if there's a short.· I'd say you'd lose your wal-wart first though!

Anyone watch Fear Factor the other night....you could film your fish tank and watch people doing the same stunt!


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02-04-2005, 09:41 PM
Somethign to think about:
If insulation on your submerged LEDs fails, there is still going to be enough resistance in the water to prevent a total short, but you might start electrolysis. Signs: bubles rizing from the submerged contacts. Depending on what is added to the aquarium water, electrolysis of that solution, can produce a number of different chemicals (also depending on material of the wires). I bet your fish are not going to like that.

02-04-2005, 11:34 PM
Why not consider using some fiber optics and mount all the electronics outside the tank, It might create a real nice effect

02-04-2005, 11:59 PM
I would pot the leds in waterproof caulking then pot it in epoxy or fiberglass....did something like that years ago using a up/down counter

Erik Arendall
02-05-2005, 01:00 AM
One thing to keep in mind is any electrical devices submerged in a fish tank could cause stray voltages. This could lead to Lateral Line Disease, fin erosion, and gill deterioration. If you see this problem you might want to get grounding rod from your local fish supply.
Since the LED's work on low voltage, i would not see a problem, just seal them up good. =)

Paul Baker
02-05-2005, 06:35 AM
I dunno about regular fish, but I know there are serious problems with electricity and sharks. They cannot be kept in captivity because inevitably there is some sort of galvanic connection in the tank (think battery) this confuses the sharks sense of direction and causes a nauseous condition in which they will not eat and eventually starve to death and these galvanic issues are in the millivolts. Just because the LED is low voltage doesn't mean its safe, so·consult with your local aquarium store before placing electrical devices in your aquarium. Now if these are just goldfish maybe you don't care but if you have a $500 fish, I wouldn't even consider doing this.

Post Edited (Paul Baker) : 2/4/2005 11:43:54 PM GMT

02-05-2005, 07:33 AM
Small world! I just received 10 tri-color leds and a PWM controller today to do the same thing. I thinking about mounting most of mine above the canopy and have the leds shine through the florescent bulbs to get the colors to blend better. One idea I had for mounting them in the water was to get some clear pvc tubing and stringing the leds through it. Haven’t figured out a good way to keep them all aligned and pointing the same way yet. Maybe a piece of formica or something to mount them on and then stuff it in the tubing.

02-05-2005, 07:58 AM
I agree with the above comment of going with fiber optics.· This way you rule out all of the above potential problems.· They are very flexible and easy to use no need to worry about water damage. All of the electronics can remain outside the tank.·· FISH SAFE...CHECK---HUMANS SAFE...CHECK---ELECTRONICS SAFE...CHECK

just my opinion.


Robert Kubichek
02-05-2005, 08:01 AM
Have you tried using milkhouse hose? I t has the advantage of being clear plastic, and easy to seal. It would not be hard to put a half inch strip of plexiglass holding the leds down it.

Shawn Lowe
02-05-2005, 10:20 PM
I did a Google search, but got nothing for Milkhouse hose. What is Milkhouse Hose?


Shawn Lowe

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Robert Kubichek
02-05-2005, 10:54 PM
It is the plastic tubing that is used in milking parlors on farms, sold at Fleet Farm stores here in WI. I have used it on my truck to keep
wiring waterproofed/protected. Also the True Value/Ace hardware store in town carries it as well, but not in as many diameters.

Good luck!


Robert Kubichek
02-05-2005, 10:58 PM
Also try this link, it has pictures; http://www.coburnco.com/display/router.asp?docid=46&itemid=837


Chris Savage
02-07-2005, 04:38 AM

·· We had recently watched a show on TV that I think explains why sharks are affected by even minute quantities of electricity...Apparently, they can sense the electrical pulses given off by other fish/mammals when they move their muscles.· Apparently they are very sensitive to this, and so I can understand what you're saying.· Interesting stuff...