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Old 10-17-2009, 10:07 AM   #1
grouper therapy grouper therapy is offline
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stray voltage and gfci (safety)

Here is a read that everyone can benefit from.
Conventional wisdom found in magazine articles and in the bowers of world wide web chat rooms indicated that “voltage” in aquaria is one of the factors that can cause Hole in the Head and Lateral Line Erosion. We read quotes like, “Stray voltage is something that exists in every tank. Stray voltage can be eliminated with a simple ground probe available at most pet shops in the twenty dollar range. Elimination of stray voltage is a simple step in reducing the stress on your fish. Every marine tank should be grounded for your protection and that of your fish.”

Is it true? Well not exactly, and as I will discuss below, the addition of a ground probe may even make matters worse!

Clearly electrical items submerged within your aquarium (power heads, heaters, etc.) can provide a direct interface between the prime power source (120 volts alternating (60 Hz) current (VAC) in the United States and 220 VAC, 50 Hz in most of the rest of the world) and the water, but some claim that the stray voltages can be indirectly induced by the lighting systems. This is possible because the skin depth of salt water (a conductor) at 60 Hz is not zero. “Skin depth” is the distance that electromagnetic energy can penetrate a conductor. Salt water is a conductor, but not a perfect conductor, so there is penetration by 60 Hz emissions. These induced voltages are small in magnitude. On the other hand, shorted pumps can develop large currents through the water, but typically between the “short” and some “ground” like your ground probe. This means that the inclusion of a ground probe could make things worse. If a pump were shorting within itself, the currents flowing through the water would remain local to the pump and should not be a problem. You would have to have two shorting pumps, or a pump and a ground probe, or some other current path to get electrical current to flow through your tank.

Direct shorts would have other ramifications. Copper or iron could be introduced into the aquarium water as plating occurred. Other compounds would plate out as well since salt water contains many ions in suspension. Electrolysis would occur, heating the water while it liberated oxygen and hydrogen. There is of course a shock hazard.

Most people do not understand the problem however. Lots of web space has been devoted to the measurement of voltage in aquariums... most of which is of no value. Voltage is not the problem, current is. Voltages can exist without there being any current. For example, birds sitting on a power line may be in direct contact with 10,000 volts, but they are not electrocuted. Why? Because no current is flowing through their bodies. Voltage is the “potential” or force that drives electrons through a conductor. The actual flow of electrons is the “current”. It is current that kills. Were one of the birds sitting on the power line to simultaneously touch one of the other wires on the transmission pole, a current path would be created (through the bird) and it would be electrocuted (and probably incinerated as well). So what are you doing when you add a grounding probe to your aquarium? You are providing a current path that might not already exist. Any fish between the source and the grounding probe will experience a current flowing through their bodies... not good!

Taking a volt meter and measuring a voltage in your aquarium relative to some arbitrary ground point does not indicate that there is a current flowing through the salt water (conductive medium) in your aquarium! It just means that the aquarium water is at a different potential than the ground reference point that you chose.

Measuring a voltage between submerged points in your aquarium may be misleading if not done correctly. The use of metallic probes can create a “battery effect” if dissimilar metals are involved (think your volt meter probes are the same metal? What if they are chrome plated (most are) and what if you’ve worn the chrome off one to expose brass or copper beneath?).

Also, some currents in salt water are perfectly natural as described below.

You can measure electrical currents everywhere-- the fact that salt water ions flow, actually generates an electrical current. Its unavoidable. The open ocean has lots of electrical currents flowing. Some of these are caused by currents flowing through the Earth while others are actually perturbations to local fields caused by the motion of objects (fish, turtles, etc.) in the water. When I was tracking the Florida Manatee (Trichechus manatus) in the Banana and Indian Rivers around the Kennedy Space center, we actually considered sensing the extremely low frequency (ELF) emissions generated by the manatee’s tails as they accelerated the brackish or salt water ions in the presence of the Earth magnetic field during vigorous swimming (alas, manatees are not very energetic most of the time and other means were chosen (Sirenian Tracking Project)). For example, the ampullae of Lorenzini in a shark’s nose detect minute current flow disturbances in the water as an aid in locating prey.

I don't use any power heads and all of my pumps are totally external and physically isolated (motor and pump head are separate). With the exception of an emergency heater in the sump, no electrical appliances come in contact with the water.

There are all sorts of anecdotes about how much better the fish in a given tank will act and look after adding one of these “grounding probes”. My belief is that if there are any stray currents in the tank coming from an electrical appliance, the solution is not to try to draw the current away with a grounding probe (symptom), rather, the appliance must be damaged and should be replaced (cure).

Fish don’t like electrical current to flow through their bodies. When higher electrical current levels flow through the water, fish will orient their bodies to minimize the potential (voltage) across their bodies, thereby minimizing the electrical current flowing through their bodies. At very low levels, the fish may only act strangely or seek areas of the aquarium where electrical current is not flowing. It is doubtful that continuous current flow through a fish’s body is beneficial, and may in fact be the source of anecdotal reports of Hole in the Head disease and Lateral Line Erosion. If your tank is at a different potential from the “ground” in your house, no electrical current may exist in your tank based on this static voltage. However as soon as you ground your tank by inserting a “grounding probe”, you will be guaranteed to have electrical current flowing even if the voltage drops.

For a technical discussion of stray voltage in aquaria and the use of Ground Fault Interrupters, click here.

In conclusion, the addition of a “grounding probe” will guarantee an electrical current flow in your aquarium and may induce erratic behavior or disease in your fish. If you have defective aquarium appliances that are creating a current path in your aquarium by using the salt water as a conductive medium, then the solution is to repair the appliances or replace them... not divert a portion of the current into a “grounding probe”.

Now for the gfci
Many folks drop a grounding probe in their tanks and connect it to a water pipe or the neutral in their wiring thereby creating a current path where one might otherwise NOT have existed. This is worse for the fish than a very localized current (short within a pump housing) or a static voltage. The Safety to the aquarist is a different issue. What about the use of Ground Fault Interrupters (GFI) to protect the aquarist?

Fuses and circuit breakers are too slow to protect one from shock . They protect equipment, not people. The GFI is electronic and faster (GFI = 10 ms). A grounding probe has to be used as a GFI reference before it will work properly. I use GFIs all over my system. It must be understood however that using GFIs on pumps and lights isn't necessarily going to stop detrimental currents in the aquarium.

For example, if one power head's hot lead (black wire) is exposed to the water and another power head's neutral lead (white wire) is exposed to the water, then there will be a current flow between them as well as any sea life that gets in the way. Lets say that both power heads were plugged into the same GFI. Since all the current coming in the black wire is going out the white wire (some through the power heads, some through the water and fish)... there is a balance, but an unhealthy one for the tank. The GFI would not trip. Adding a ground probe would cause the GFI to trip in this example.

Second example: If a GFI is used on the pumps and lights and there is a grounding probe in place, any "induced" voltage will cause a current through the water and out the ground probe. Light, heat, motion, and induced electrical currents all represent "consumed energy". The current into the "emitter" of these energies will be the same as the current going out of the emitter. The circuit is balanced and the GFI will not trip, but energy is still created in various forms which can be transmitted to the aquarium. Consider an improbable case that will illustrate this point.

Suppose I had a motor (like we'd find in a power head) and I supply it power from a GFI-protected source. Then I properly install a ground probe. Now lets say that I connected an electrical generator to the motor through an insulated mechanical coupling. When the motor is turned on, it turns the generator which in turn creates a voltage. I will then connect one side of the generator to ground and the other side to my aquarium water. What will happen? Current will flow through the aquarium and out the ground probe. Will the GFI detect this and trip? No, because even through its current results from the motor-driven generator's energy, the motor's lines remain balanced.

So now we have a system that can electrocute both the aquarist and the fish even though there is a properly installed GFI and ground probe. Were I to remove the ground probe, there would no longer be a current path affecting the fish (they are now the "birds on a wire"). The aquarist however, is still at risk if he touches the water and a ground.

In reality, induced voltages and currents will be small... so small that they are probably NOT an issue for the safety of the aquarist, but with a grounding probe present, they could be unhealthy for the fish and coral (and I suspect they probably are, since sea life has little insulation to mitigate the current flow through their bodies. I can't believe that a continuous current flowing through one's body would not cause havoc with cellular ion transport, not to mention the "jamming" of sensory organs).

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Old 10-17-2009, 10:27 AM   #2
Hackman72 Hackman72 is offline
 
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uhhh, yeah...that's what I was thinking too

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Old 10-17-2009, 10:34 AM   #3
Hackman72 Hackman72 is offline
 
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seriously though, I actually understood most of it with very little knowledge of electricity. Thanks for taking the time to post that.

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Old 10-17-2009, 10:43 AM   #4
JennM JennM is offline
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Great article This should be placed somewhere on the site for people to refer to it.

I have some observations that may lead to more discussion.

It has been my observation that when other factors have been ruled out (water quality, diet), and a fish presents with HLLE, we check for stray voltage using a volt meter. Typically we find it... I've seen everything from about 18 volts to 160 volts. Then we go through process of elimination to figure out which device(s) are casting the voltage, and we replace them. Usually that solves the problem and if we caught it early enough, the physical symptoms of HLLE begin to reverse.

Is there a better way to test the aquarium for the presence of current? If so, I'd like to learn about it. Or is the "voltage" I'm finding, a coincidence?

Other things we've seen anecodotally, that we've blamed on voltage is recurring cases of ich, and even otherwise healthy looking fish going "nuts" and plowing themselves head first into rocks to die (esp. wrasses). Again if we see these things and have ruled out other causes, we check for voltage and usually find it.

Years ago, Lifestudent (Bob) was having an ich problem. He'd done everything by the book - quarantined all new acquisitions, left the display fishless for a couple of months... the works. Each time he would re-introduce specimens into the main display, they got ich. I'd been over to his home several times - couldn't figure it out - water was perfect, quarantine protocol was fine, diet was good... fish from different sources etc., but the result was always the same.

After much angst and head-scratching, I did some online research and found an article about voltage, so we bought a volt meter and tested... I think it was something like 38 volts. So we started unplugging devices etc., and we found the culprit was actually the shop lights he was using over the tank (75g). I cannot explain how the volts were getting into the tank from the lights, but it was.

He replaced the lights - re-quarantined and re-treated the fish... problem did not come back.

I saw this happen with another customer too - 55g tank, her Coral Beauty started showing symptoms of HLLE, and we ruled out water quality and nutrition. Did the same thing - her husband tested for voltage. Her equipment was new as she'd recently upgraded tanks... the only item they'd used that was old was the light timer. It was the timer that was bad. Again - I cannot explain how a timer on a wall nowhere near the tank was causing volts in the water - but that's what it was. Timer was replaced, symptoms reversed.

Most often when we see this sort of thing it's the heater. I have a several tangs in the shop that were given to me damaged from scarring of advanced HLLE. 2 of them came from tanks where voltage was detected after the fact (heaters again). 2 came from a tank that hadn't had water changed in 2 years... I don't know if it was voltage or water quality (he fed a varied diet) - I didn't have a chance to test that one. I also have a large Koran angel that was traded to me with a bad case of HLLE and he's on the mend, but the source of that is unknown.

None of the tanks where we've found voltage had a grounding probe (and I doubt they had GFCI either, but we use and recommend them!)

I absolutely agree that a grounding probe is not a substitute for repairing/replacing whatever was causing voltage.

Another observation... my service technician can "detect" voltage if she has a cut on her hand, and puts her hand in the tank (not a testing method I recommend!). Of course this talent was discovered by accident. She was servicing a tank and she had a little cut on her finger and when she put her hand in the tank, she felt a tingle. She tried putting the other (uncut) hand in the tank... no tingle... after doing this a few times (!!!!) she decided to go back with the volt meter... 94 volts. That (possibly) explained why the yellow tang had HLLE and we couldn't figure out why.

Now when we see the first signs of HLLE, we automatically check for voltage, in addition to checking water quality and verifying that the keeper is feeding a varied diet that includes greens. We find voltage, fix the problem, and the HLLE reverses.

I know there are still many arguments out there that may not support these observations of ours, but I've seen it too many times to dismiss it.

If there's something else or some better way to test this, I would be very interested in learning more.

Jenn

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Old 10-17-2009, 11:59 AM   #5
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The tingle that she felt was absolutely current through her body no doubt,I have experienced the same thing usually barefoot or holding some type of ground. The reason I posted was that sometimes if you feel the current doesn't mean the fish does. A circuit has to be closed for current to flow. Like the bird sitting on one 12.000 volt line he is fine ,let him close the circuit by touching a ground and its off to KFC. You could have a 12,000 volt line in your tank and not feel a thing until you closed the circuit then things would get a little warm! A grounding probe can actually add to the problem. The best thing to do is remove the source like Jenn does and problem solved. So far as the florescent lights adding current to the tank it is usually the static electricity that they produce that does it. So far as stray voltage hurting or stressing the fish and causing the different diseases I totally agree,it would me.

As for gfci protection I am sorry for the lengthy read but if you do not understand the article please have an electrician check your system! If not properly installed it could give you a false sense of safety.

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Old 10-17-2009, 12:08 PM   #6
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Don't apologize - I think you spelled it out quite succinctly.

I was told by someone that you may not feel volts, but you will feel amps. Your thoughts?

I know where I used to work once I had hands in a tank and my elbow (attached to the arm in the tank) bumped a metal light fixture and I got a little jolt off that... I figure that my touching metal completed a circuit, yes?

I am glad we have GFIs here... once I knocked a light fixture into the rock vat and it kicked the breaker off pretty much as soon as it hit the water. I didn't have hands or anything in the water - but if I had, I'd have been glad the breaker kicked off right away.

I know somebody who did not have GFI, and he dropped a light fixture into his 1200g tank. He was standing on a ladder when he did it, and instinctively he reached to grab the light as it fell but it was too late. Current went through his right side, across to his left side and his left shoe was smoking. He drove himself to the hospital (!!!) and he checked out OK but the doctor told him he was lucky he didn't kill himself.

Water and electricity can be dangerous stuff.

Jenn

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Old 10-17-2009, 12:09 PM   #7
DrNecropolis DrNecropolis is offline
 
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Barry and I were discussing some issues I have been having lately and decided to test for stray voltage.. 25volts.. I have seen no ill effects to any live stock and haven't been shocked.. Oddly enough, unplugging things one by one,.. Never dropped unplugged the actual DC8 from the wall with nothing plugged into it and it went from 25 to .53 volts.. Still trying to figure out what's going on..

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Old 10-17-2009, 12:47 PM   #8
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With out going in to a bunch of jargon and terms. What you feel is the effects of volts, amps and ohms all acting together. The saying you have heard is probably (volts don't kill people amps do) which is basically true. What you feel is current and the only way to have current is a completed circuit .

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Old 10-17-2009, 12:48 PM   #9
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Quote:
Originally Posted by DrNecropolis View Post
Barry and I were discussing some issues I have been having lately and decided to test for stray voltage.. 25volts.. I have seen no ill effects to any live stock and haven't been shocked.. Oddly enough, unplugging things one by one,.. Never dropped unplugged the actual DC8 from the wall with nothing plugged into it and it went from 25 to .53 volts.. Still trying to figure out what's going on..
Is that 53 or .53 ?

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Old 10-17-2009, 12:54 PM   #10
DrNecropolis DrNecropolis is offline
 
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.53 with the DC8 unplugged and 25 with it plugged in to the wall and nothing plugged into it..

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Old 10-17-2009, 1:26 PM   #11
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That might be a little feed back from the neutral and or ground side of your breaker box. not that uncommon.

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Old 10-17-2009, 1:27 PM   #12
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I still recall that issue from 2002 all too vividly!

I'm glad that we finally figured out that it was voltage!

Thanks Jenn for your help on solving that problem!

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Old 10-17-2009, 1:40 PM   #13
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Yep, and we were just talking about it recently too. For what it's worth - that tribulation was worth its weight in gold for others who encountered similar problems - we learned a lot from that which helped others.

Jenn

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Old 10-17-2009, 1:58 PM   #14
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Originally Posted by grouper therapy View Post
That might be a little feed back from the neutral and or ground side of your breaker box. not that uncommon.
What exactly do you mean by this? What exactly is "feed back from the neutral and or ground"? How can this induce 25 volts into this tank with nothing connected to it?

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Old 10-17-2009, 2:05 PM   #15
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I don't run a grounding probe on my current system (no pun intended) but do run GFCIs on everything. Periodically, one of them will begin to "randomly" trip and eventually the defective power head or heater will be found. I wouldn't run a system without a GFCI but I am undecided on the need for the grounding probe.

On one hand, the grounding probe will help trip the GFCI when current is leaked to the tank, on the other, the GFCIs will trip once a path to ground is made. On one hand, the fish tank is like the bird on the wire, in the other, the tank has no leaked current. Both seem OK to me and the grounding probe seems a touch safer to us humans.

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Old 10-17-2009, 2:09 PM   #16
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I was thinking it could be the operating voltage of the eternal relays in the dc 8. I have experienced the same on some industrial controls when low voltage relays were used to switch devices. Do you have another theory?

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Old 10-17-2009, 2:40 PM   #17
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Great read!

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Old 10-17-2009, 4:46 PM   #18
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Quote:
Originally Posted by Schwaggs View Post
What exactly do you mean by this? What exactly is "feed back from the neutral and or ground"? How can this induce 25 volts into this tank with nothing connected to it?
Sorry I did make an assumption that the control cable was still plugged into the
the dc8 and that he was referring to no devices (lights pumps, etc) were plugged in. All neutral legs in a circuit usually have some voltage as well albeit small they do have some. Except three phase which I think is earth grounded at the transformer don't quote me on that one. That being said the relay in the dc 8 that might be in the always closed position might allow the small voltage coming from the neutral to energize the circuit that other device in the aquarium share with the dc8.

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Old 10-18-2009, 10:35 AM   #19
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What is the exact way for testing for electricity in a tank? I do have a multi-tester already so I'm good there. Not that I'm having any sort electrical problem, I just want to know for future use.

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Old 10-18-2009, 5:30 PM   #20
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i have the gfcion all my outlets and i have a ground probe.so do i need to pull out the probe or what please let me know thanks

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