Using Ground Probes in Aquariums

Brew12

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Seawitch submitted a new Article:

Using Ground Probes in Aquariums

Note from the Editor: Some time ago, our resident electrical guru, @Brew12, wrote a good article on the forum at the beginning of a discussion thread about using ground probes for your aquarium. As soon as I saw the article, I recognized that this deserved top billing. So, here, below, is our resident electrical guru's suggestions on ground probes in his own words. Hint: You need one.

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Photo by rawpixel.com from Pexels

Why is it that some people refuse to put a grounding probe in their aquarium? I've seen many arguments against using them, some of which are based on what I believe to be bad information.

I want to make the case for why every aquarium should have a grounding probe installed.
We have these beautiful aquariums full of salt water into which we place electrically operated equipment. Everyone has heard the phrase "Water and electricity don't mix" and it is especially true of salt water. Yet this doesn't have to be dangerous and a ground probe is key to making this safe.

An electrical shock occurs when current flows through a person. There are three main factors that impact the severity of the shock. The amount of current flowing through the person, the length of time they are being shocked, and the path the current takes through the body.

For a shock to occur, a person must be touching an energized conductor and a source to ground. The glass and acrylic most aquariums are made from are excellent insulators. If a pump or heater develops a fault in the salt water, it will raise all of the water in the aquarium to the same voltage as is available at the fault, typically close to 115V. If you are touching the metal housing of a light fixture or standing on wet concrete and touch the water, you become the best path for the current to take to get to ground. These shocks are most likely to take the most dangerous path, which is through our heart. It will go into the hand, through the heart, and either out the opposite hand or down through our legs.




This is one way the ground probe keeps us safe. Electricity always takes the lowest resistance path to ground. The human body does have some resistance, so a properly maintained ground plug will always offer a lower resistance path to ground.

I would also make the argument that the use of a ground plug is important to the health of our marine fish, but not because of a risk of electrical shock. Scientists use electro-fishing techniques to collect or count fish populations by shocking fish. Electric eels hunt prey by shocking them with electricity. So why do I say marine fish are not at risk for being shocked? They live in salt water. Electric eels are a fresh water species and electro-fishing only works fresh water. In a fresh water environment the fish is more conductive than the water just like people are more conductive than air. You cannot shock a marine fish while it is in salt water since the water is more conductive than the fish. This doesn't mean that marine fish aren't affected by electricity.

It is a generalization to say that all of the salt water is at the same voltage in our aquariums. In reality, small differences in potential can exist within the water. Eddy currents of water will cause a difference in voltage. There will be a difference in potential caused by any air bubbles that may touch a fish. While these may not cause shocks, it can cause a serious irritation across the surface of the fish.

I would also point out that you do not need to have an electrical fault to have a harmful voltage in your aquarium. Any energized cord either running in the water or along the outside of the tank will create a voltage in the tank using a process called induction. This is why many people see a voltage in their aquariums without having a GFCI breaker trip. A ground probe will prevent any voltage from building up in the aquarium water, protecting our fish from these small voltage differences.

Grounding probes also protect our tank from another problem that is much harder to see and correct. If you have an electrical fault in your tank, there is a high probability that you have exposed copper in your system. This copper will corrode in salt water and the corrosion is accelerated when impacted by electricity. Even if you use a GFCI, the circuit will not trip on a fault until you have a source to ground. A ground probe will immediately provide that path to ground. If you do not have a ground probe installed, you could be leaching copper into your system for days or longer until a path to ground from your water is established.

The one argument against using ground probes I cannot counter is that it could provide a heat source during an electrical fault. If you have an electrical fault in a very narrow resistance range, and do not use GFCI protection, it can act like a heater. I know I wouldn't risk the safety of my family and friends in an effort to avoid this one scenario. I hope after reading this you won't either.

Does your aquarium system control panel look like this? Then get a ground probe.

This is a royalty-free image from Pixabay.

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Author Profile: @Brew 12

Steven Frick has spent much more time under the ocean than keeping a small piece of it. He got his start in the electrical field in the US Navy Nuclear Power program as an electrician's mate. After 5 years of service on the submarine USS Henry M Jackson he finished his final 3+ years of service teaching electrical theory at the Knolls Atomic Power Laboratory.

Currently, he runs the projects and maintenance for the power distribution system of one of largest electrical consuming heavy industrial companies in the Southeastern United States. He wrote his sites' electrical safety policies and routinely acts as a consultant to other industrial facilities looking to improve their electrical safety programs. As someone who loves to both learn and teach, he has focused his attention on his newest hobby, reefing.
 

Ron Reefman

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As a maintenance guy for many years, I've done my share of electrical repairs and new installs. Steve lays it all out perfectly here. Get a grounding cord!
 
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Brew12

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What's the best grounding probe material for use in a marine aquarium?
All of the ones I'm familiar with are titanium coated.
 

dansreef

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Great Article.

I have had a grounding probe on my tanks for years. I have never had issues. I read an article years ago and borrowed a friends volt meter and saw stray voltage in all of my systems. I quickly ordered grounding probes. Why not? Not like they are expensive compared to the crazy money we spend on other equipment, corals and fish. If it can protect me and my family from a shock, it is a good investment.
 

leepink23

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Great Article.

I have had a grounding probe on my tanks for years. I have never had issues. I read an article years ago and borrowed a friends volt meter and saw stray voltage in all of my systems. I quickly ordered grounding probes. Why not? Not like they are expensive compared to the crazy money we spend on other equipment, corals and fish. If it can protect me and my family from a shock, it is a good investment.
Where did you order from?
 

ca1ore

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Question for the author. I use a probe in my sump because that’s where most of my equipment is (and I still stand on a slab of styrofoam). I don’t use a second in the display because all that is there are vortech pumps or low voltage DC pumps like the WAV. Is that flawed logic? I have never felt any tingles from the display and multimeter reads zero.
 

dansreef

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Question for the author. I use a probe in my sump because that’s where most of my equipment is (and I still stand on a slab of styrofoam). I don’t use a second in the display because all that is there are vortech pumps or low voltage DC pumps like the WAV. Is that flawed logic? I have never felt any tingles from the display and multimeter reads zero.
That is a good question. I do the same. My grounding probes are in the sumps, one of which is in the basement.
 
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Brew12

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Question for the author. I use a probe in my sump because that’s where most of my equipment is (and I still stand on a slab of styrofoam). I don’t use a second in the display because all that is there are vortech pumps or low voltage DC pumps like the WAV. Is that flawed logic? I have never felt any tingles from the display and multimeter reads zero.
I don't believe that the logic is flawed, especially if you use the ground probe in conjunction with GFCI. I do the same thing.

With flow through the system the seawater electrically connects the DT to the sump. You lose this connection with the return pump off but in your situation there is no risk because your motors are outside the tank or low voltage.

I would be comfortable doing this even with 120VAC powerheads. The only way a person wouldn't be protected in the DT is if one of the powerheads failed while the return pump was off. If the pump failed before the return pump was turned off it would trip the GFCI. Odds of this happening is pretty slim imo.
 
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Brew12

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What product's are people recommending?
I can't say I've ever recommended a particular product. These are very simple devices. It is a titanium rod connected to a copper wire which connects to a ground prong on an outlet. Risk of low quality material or improper molding is a concern so I would order from a reputable supplier. I do recommend getting one with what looks like a traditional cord plug. Some only have a ring terminal which can be a little more challenging to use.

Marine Depot offers this one which has the ring terminal and a cord plug.
https://www.marinedepot.com/Titanium_Ground_Probe_GFCI_Extension_Cords_Grounding_Probes_Surge_Protectors_for_Saltwater_Aquariums-TAAM_Via_Aqua-TA1111-FIMIGF-vi.html
 
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Brew12

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What do we do if we don't have grounded outlets in our home?
That is a tough situation. You can still use a GFCI but a grounding probe won't do you any good. I realize it isn't the cheapest thing to do, but I would try to budget getting the house wiring replaced to update the outlets. It makes using any 3 prong devices unsafe, aquarium or not.
 
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Brew12

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Correct me if I’m wrong but an older house without grounding uses metal boxes with metal armor cable, so can’t you simply ground to box?
It is possible as that was done for at least a few years. And yes, you could do that if this is the case. In many older homes a 2 conductor wire was run to the outlets so no ground is available.
 

vetteguy53081

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I consider these one of the cheapest yet beneficial items within a reef system as salt is very conductive in water and prevents the chance of shock to both tank and reefer

 

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