Voltage in tank

[Woodneers]

measuring 30 volts from sump to ground. No shocks felt by me but what are my inhabitants going through. I can unplug powerheads and make the value drop little by little. Should I add a grounding probe?

 

[Brad Miller]

Ground probes are not at all what they are cracked up to be.
Robert Michelson said this...

Principal Research Engineer, Emeritus - Georgia Tech Research InstituteAdjunct Associate Professor (Ret.) - Georgia Institute of Technology President - Millennial Vision, LLC.

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 tankshould 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 currentflowing 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.

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”.

 

[DirtDiggler2823]

great read. Thank you.

 

[UCF Alum]

Check this...

https://www.reef2reef.com/threads/stray-voltage-talk.459970/

 

[Brew12]

Ground probes are not at all what they are cracked up to be.
Robert Michelson said this...

Principal Research Engineer, Emeritus - Georgia Tech Research InstituteAdjunct Associate Professor (Ret.) - Georgia Institute of Technology President - Millennial Vision, LLC.

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 tankshould 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 currentflowing 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.

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”.

I've reached out to this guy repeatedly with technical explanation on why his blog post is wrong. Unfortunately, I have been unable to reach him or he is ignoring my attempts to contact. I would highly encourage everyone who comes across this post, wherever they may find it, and ignore it. There is enough correct theory to make it believable until you realize how incorrectly that theory is applied.

 

[Brad Miller]

Please explain why you think it is so wrong,
I have an extensive background on these types of subjects and find it to be very credible.

The point of the article is not to use a ground rod but to rely on a gfi circuit

 

[Brew12]

Please explain why you think it is so wrong,
I have an extensive background on these types of subjects and find it to be very credible.

The point of the article is not to use a ground rod but to rely on a gfi circuit

The main issue with his post is that he doesn't take into account that the water around the fish is much more conductive than the fish itself. This causes the vast majority of current to flow around the fish. This is why you can't electrofish in salt water, only fresh water.
He also doesn't take into account the current fluctuations between inductive/capacitive sources or their phase angular relationships. Putting in a ground probe doesn't increase current flow at all. If anything, by adding a resistive component, it will reduce current flow in the tank.

I agree it comes across as credible, which is part of the problem. Just like the guy who posted the You-tube video where they put a ground probe into a bucket of water with a bare wire and they still get a voltage. He doesn't tell you he is using tap water anywhere in the video, and the video is about reef tanks. Unfortunately convincing yet very incorrect.

 

[Brew12]

Please explain why you think it is so wrong,
I have an extensive background on these types of subjects and find it to be very credible.

The point of the article is not to use a ground rod but to rely on a gfi circuit

Since this is your background, hopefully you have been exposed to this equation for electrical density for induced sources. You can fairly accurately calculate the expected voltage in your tank based on your cable lengths and current flow.

If you run the numbers, you will see it is highly unlikely to have more than .07 amps due to voltage induced in your system. Fish are roughly 5000 times more resistive than water so they only see 1/5000th of that .07A.

 

[Brad Miller]

I see what point you are trying to make...
I list points below for my argument;

1. Installing a grounding probe may seem like a good thing for protecting a human, but possibly not so good for a fish or invert.

I would think that there haven't been too many studies on the conductivity of livestock inside a saltwater environment, other than the people who electrocute fish to harvest them.

Without spending a lot of time on this, I came across a study done by those companies awhile ago and they sacrificed some fish and found them to have an immersion conductivity of 72–204 μS/cm (which I'm sure can be greatly varied due to the type, size etc of the fish)

2. Induced voltage is a normal and natural thing in our reef tanks and would be measured only with the proper meter.

3. Stray voltage is quite another issue, this would originate from a faulty device inside or in touch with our tanks, and should be measured with the proper meter.

4. Both induced and stray voltage are harmless unless they are given a path to ground. Installing a grounding probe will create that path and now you have created current flow through you water to ground. Have you protected a human body from possible tingle of low or high current flow (yes)
Have you now created a potential 24/7 hazard for your livestock (yes)
Any amount of current no matter if nano small dectable, would not be good for any livestock.

5. Installing a gfi receptacle or breaker is the real answer to protecting both human and livestock since they will trip in milliseconds, thereby reducing a chance of fatality by electrocution.

6. Installing a grounding probe for induced or stray voltage is just covering up a potential problem and instead, I would suggest locating the source and correcting it, along with installing a gfi circuit.

7. At the end of the day, who are we to assume anything, protect yourself and your livestock

 

[Brew12]

Let me address some of this.

1) I agree that there has been little studying done on the impact of current on marine fish. You cannot electrofish in marine water, so no studies have been done along those lines either. To stun a fish with electricity would require enough current that you would boil the water around the fish before the current had an impact. There have been studies on the impact of electricity on coral. There are reef restoration projects ongoing that use electricity to stimulate the growth of coral to seed new reefs.

2) and 3) Induced voltages can be read with a normal meter as can stray (fault) voltages. A specialized meter will help determine which is which but most off the shelf voltmeters can read both.

4) In the high voltage world we use a technique called equipotential grounding. We attach copper cables to the de-energized transmission lines we are working on and then connect those cables to ground. This protects us from induced voltages that can build up on the lines and also help protect against the lines being inadvertently energized. The fish live in a conductor so their entire world is equipotential. In theory, there is no negative impact of taking their equipotential world and tying it to ground. The fish have no way to know what voltage level they are being referenced to.
As for any current being bad, that may or may not be true. If it is true, then we should not have more than a single electrical device in our tanks. Currents will circulate throughout our system between these devices. If anything, a ground probe will shorten the path these tiny induced currents travel by shunting it to ground. But lets look at this, too. Conductivity of seawater is around 50,000 us/cm. Even using the most conductive fish in the numbers you posted, that still means for over .1A of total current flow (unrealistically high for an induced voltage in an aquarium) that would still be under 0.004A through the fish. And I can't stress enough.. this current is already flowing through the system regardless of if you use a ground probe or not.

5), 6) and 7) I completely agree that a GFCI is the way to go. They will work best when used in conjunction with a ground probe. If all of the voltages are induced the ground probe will reduce the distance these currents travel. If it is a fault voltage, the GFCI/ground probe combination will de-energize the failed component immediately. Without a ground probe, the failed component will likely not trip the GFCI since no current is flowing to ground until someone puts their hand in the water. During this time, that energized conductor will be contacting seawater. That conductor is most likely copper. Copper will corrode in seawater and it will corrode faster if energized. To protect my livestock from this possible copper contamination (not to mention melted plastics and the like) I depend on both a GFCI and a ground probe working in tandem.