Please visit our Sponsors
FAQs about Grounding Probes and Aquarium Systems

Related Articles: Marine ElectricalMarine Aquarium Light Fixtures and Canopies GFCIs and Marine AquariumsPump Problems

Related FAQs:  Electricity FAQ 1, Electricity FAQ 2, GFCIs and Marine Aquariums

Yes, even invertebrates can be shocked! Seriatopora caliendrum

Stray voltage/ current, probes... induction, fixing!   8/11/10
Hey Crew,
<Hi Jimmy>
I have a question re: stray voltage/ current in my marine tank. I have a very small cut on my finger and I noticed that my 80g marine QT has stray voltage ( only place I feel it is inside the cut ) the voltage seemed to be coming from a Mag drive 5 so I changed it out and put a grounding probe in the sump of the tank. As I was doing my tank maintenance I again noted stray voltage. This time I thought it was the titanium heater, which I removed but to no avail. I then removed the grounding probe and the voltage was gone.
To investigate further I connected the grounding probe to various outlets that are in the same loop in my garage, put the probe in a glass of water and noted the stray voltage again ! ( only in the area of the small cut on my finger ). I tested other outlets inside the house as well as my main display upstairs ( different system ) and I detected no stray voltage. It seems to me that there is a small voltage current in the ground loop of my electrical system that in part grounds to me or the tank when I use a grounding probe ( i.e. some of the current preferentially finds the tank instead of the house ground ) that I can only detect through the cut in my finger. I have been told that my electrical system is properly grounded, and that what I am experiencing is not uncommon. It is called ground loop interference and occurs when a grounded circuit has yet another place to ground itself other than the main grounding pin in to the house. When two or more devices are connected to a common ground through different paths, a ground loop occurs. And there is no such thing as a perfect ground. The problem seem more intense when multiple aquarium devices are grounded to the same power strip or outlet. ( which makes sense )
If I can feel it through the cut in my finger I imagine the gills of an animal are probably even more sensitive !
Any suggestions ?
<The first thing to try is adding a grounding rod in the garage (or right outside). They are right around $15 at a hardware/electrical store, plus a little for connectors and a wire.>
<Scott T.>

Electricity And A Saltwater Aquarium 3/13/10
<Hello Shawn>
I have a few questions relative to electricity and the saltwater aquarium.
I have a Smart UPS that I am using to provide power and back up a 30 gallon fish and invertebrate aquarium. I have the UPS plugged into a GFCI outlet and various submersible pumps and a heater plugged into the UPS outlets.
Is this the proper setup when using a UPS? I am not sure if the UPS outlets are in turn protected by the GFCI outlet.
<Anything plugged into the GFCI outlet will be protected. Do ensure that your UPS has the capability of handling the wattage/current of the devices plugged into it.>
I have also measured stray voltage to be around 40Vac by using a multimeter with 1 probe in the sump water and the other in the ground of an outlet.
Is this considered a normal reading?
<You should read 0 providing there is indeed a ground wire hooked up to the outlet ground. If your home is an older home, the old two prong outlets may have been replaced with grounded outlets to avoid the use of adapters and it is possible that no ground wire is connected to the ground terminal.
I would recommend the use of a ground probe even though you are using a GFCI. Sounds like one of your devices has a voltage/current leak and I'm sure this device had this problem before you plugged it into the GFCI and is the reason why the GFCI did not trip. GFCI circuitry measures current going into the device on the hot leg and looks for the same current on the return leg (common). If the slightest change occurs, it will trip. If the device was defective/leaking before you plugged it into the GFCI, (and this is why I recommend a ground probe in addition to the GFCI) it would not know the device is defective as it sees no current change going into and out of it. If the device went bad/leaked while plugged into the GFCI, it would trip, as it would sense a current change going into and out of the device.>
I do not have a ground probe and have seen much debate on whether they actually provide additional safety. Would you recommend a ground probe?
The tank has been running for 1 year with this voltage present.
<You need to set up your multimeter in the manner you mentioned above, then unplug one device at a time until you read 0 voltage, once the culprit device is found, I would strongly recommend replacing it. Do make sure your multimeter is set to AC voltage and select volts, do not use the millivolt setting. If you were grounded when you placed your hands in the tank, the GFCI would instantly trip as it would sense a loss of current, as much of it would be going through you to ground.>
<You're welcome. James (Salty Dog)>

Re Electricity And A Saltwater Aquarium 3/15/10
Thanks for the advice.
<You're welcome, Shawn.>
I have a new home and the GFCI outlet is new with proper grounding.
However I would like some further clarification regarding your suggestion that the stray voltage reading should be 0. Do you mean with a ground probe installed?
I made some more detailed measurements and each device was tested separately without any other devices plugged in. All devices are less than a year old and are located in my sump/skimmer.
Pump: 18.45VAC
Heater: 16.65VAC
Skimmer: 18.73VAC
With all items powered the voltage is around 40VAC. Based on the above measurements, I think it is common for "healthy" submersible devices to induce voltage in water.
<Yes, they are considered inductors and can create stray voltage in that regard, but if the tank water is indeed grounded, you should read no voltage, the induced voltage should be going to ground.
There are some UPS devices that use isolated ground circuitry and are considered above ground devices. Try measuring the voltage without the using the UPS device and see what you get.>
I will get a ground probe and re-check.
Any further advice is greatly appreciated.
<Not yet. James (Salty Dog)>

Re Electricity And A Saltwater Aquarium 3/15/10
I have measured the devices without the UPS and get the same readings. You made the statement "Yes, they are considered inductors and can create stray voltage in that regard, but if the tank water is indeed grounded, you should read no voltage, the induced voltage should be going to ground."
Without the use of a ground probe, how will the tank water be grounded?
<Exactly my point, and wanted to prove this out to you. GFCI's do not ground your tank water, they just provide protection should you become grounded and place your hand in the water with stray voltages present.
A ground probe will eliminate these induced/stray voltages and is also much better for the animals in your system.>
All of my devices that are submersible do not come with 3 wire cords.
<You're welcome. James (Salty Dog)>

HLLE Related To Stray Voltage?
Ground probe 3/20/09

Hello crew and thanks for all the great advice.
<You're welcome.>
The question has been asked before regarding the value of a ground probe.
I am in agreement with the argument that the probe completes the circuit and the resulting flow of
current is a bigger problem from a fish and human safety perspective. I have a 125g FOWLR with powerheads and heaters in the main tank and the following fish: Powder Brown (A. japonicus), Tomini Tang, Flame Angel and an Assasi Triggerfish. The Powder Brown, Flame Angel and Assai are fine,
but the Tomini has what appears to be mild HLLE on his forehead and it has been very slowly increasing in size for the past 6 months. Also the behavior of the Tomini is more reclusive then active, color is good and
seems to only like to eat New Life Spectrum pellets along with grazing the rock and tank walls. I feed a varied diet ( New Life Spectrum various pellet formulas, Nori, Formula II, Mysis and supplement with Selcon). I decided to try the ground probe and I have noticed an immediate change in behavior. The Tomini is more active and less reclusive and now regularly eats Nori. The mild HLLE seems to be slowly improving, but its to early to be certain. The other fish have not changed their behavior. The equipment
in the tank is working fine and all are connected to GFIs. I plan to experiment some more to better confirm if the ground probe addition is the primary reason for the change in behavior. I also speculate that if the
ground probe is a benefit then maybe the Tomini is just more sensitive to very low electric fields relative to the other species in my tank. The question is has there been any new information on this topic that may help
clear up the controversy or is this still just a myth?
No myth, has been cited several times/places and your experience does not surprise me.
If you had any stray voltage/current in your tank it would be very low due to your GFIC protection. GFIC's will trip when a difference of 5 milliamps (.005 A) is detected. Simply said, if .25 amps are going out to the
component, .25 better be coming back or the GFI will trip. As to new info on HLLE, none that I'm aware of. Do some Googling, and thank you for sharing your experience with us.>
Thanks again.
<You're welcome. James (Salty Dog)>

Fish Recommendation for a reef, grounding probe maint., Clown comp.   12/5/08 Second question; Is it a problem if my grounding probe gets covered in algae? <Mmm, not really... or at least not much> <And Neale has responded to your FW queries... In future, please isolate/send your questions one topic/subject at a time. Thank you, Bob Fenner>

Grounding Probe Info 4/23/08 Dear Crew, I was doing a little research on grounding probes and came across this article written by a Georgia Tech professor, and thought I'd share: http://avdil.gtri.gatech.edu/RCM/RCM/Aquarium/GroundingProbes.html Basically, he educates the reader on the difference between voltage in the tank (not a problem) and current in the tank (a problem) and concludes that the addition of a grounding probe more often than not causes a current problem where none previously existed (the website also contains a good discussion about GFI outlets). Although I don't know the author and can't vouch for his wisdom, it seemed to make sense to me. This article was a real eye opener for me--not because I was moments away from wasting $22 on a grounding probe, but because every single catalog and every single e-tailer I see sells and touts grounding probes. <I do not... and have not... all these decades...> I assume that there are cases in which they have some benefit, but I came away thinking, gee, this is like "reef safe ich killer" and many of the other products I see you guys poo-poo as worthless snake oil--it's amazing to me that people can legally make tons of money off of hobbyist by selling stuff that doesn't actually work or even causes harm. Cheers, Andy <Agreed... and this is indeed a very fine piece... and the link to this gentleman's tank project period: http://avdil.gtri.gatech.edu/RCM/RCM/MICHELSONAquarium.html Thank you for sending this along. Will post/share. Bob Fenner>

Re: Grounding Probe Info... and the meaning/liability for the term/label "reef safe" Bob, <Andy> That guy's site is really interesting/insightful. Because I've never used anything that claims to be "reef safe", I've never had the opportunity to read the label or warranty (if there is one) on "reef safe" medications as to who bears responsibility when a hobbyist uses such a product and his/her reef dies (or maybe nothing dies because it's just colored water?). Something tells the manufacturer disclaims liability. <I have said on occasion that I do wish I had the time and/or money to hire someone in the legal biz to challenge (i.e. sue) the many folks who make such disingenuous products... "If only...". BobF>

Re: Grounding Probe Info Was that a subtle nudge?? ;-) <... always> Ah, we could spend many a keystroke discussing this topic. In some ways I am surprised it has not happened. Lawyers tend to have more money than the average Joe = bigger/more expensive tanks = bigger/more expensive crashes from use of dubious products = higher $ damages. The problem with your dream is that you need one of the following (i) a lawyer who's been personally screwed and is willing to shoulder the legal battle, (ii) a rich hobbyist willing to pay a lawyer by the hour (not likely) or (iii) a pot at the end of the rainbow for a contingency fee lawyer (i.e., a big enough class of plaintiffs who have been harmed that a lawyer's 35-40% fee is big enough to take the case). My guess is that the warning labels on these products make it clear that "we cannot guarantee that nothing will die from this. Of course it is best to treat in a separate hospital tank, and the hobbyist assumes the risk of adverse effects if used in the display." <Well put> Every consumer product comes with a warranty of merchantability (i.e., a warranty that the product does what it says it will do). Generally, a manufacturer cannot disclaim such a warranty in a consumer transaction. To pursue such a claim takes a lot of time and, if you hire a lawyer, money. The court system is so expensive and time consuming these days that it makes pursuing these claims difficult. There is always the state's attorney general/consumer protection division, but my experience is that regulators are loathe to take on such matters unless there has been a significant financial harm. <Mmm, our system of jurisprudence/litigation is the element of being a U.S. citizen that I "like" best/worse about America. Cheers, BobF>

Grounding Probes - 4/22/07 Hi, <Hello.> I checked on WWM under 'electricity' and did not see information on grounding probes. <Using the Google search feature reveals many references to them, although there are varying opinions of course. Bob doesn't seem to be a fan.> <<Thank you Alex... I am not in most "cases", arrangements... Better money/attention paid to using GFCIs, polarization, better wiring period. RMF>> I am having a difficult time on deciding whether I should use a grounding probe.  Searching the web, I find many sources saying grounding probes are a must for aquariums.  On the other hand we have the article on why not to use them: http://avdil.gtri.gatech.edu/RCM/RCM/Aquarium/GroundingProbes.html which makes sense to me.   <This does make some good points.  The part that I don't agree with is the amount of current they seem to think will be flowing through the ground and the fish.  While the induced voltage can build up to a pretty high level in the tank, this is over time, and once grounded the amount of current flowing to keep it grounded constantly will be negligible, unless there is an actual problem with electrical components not being properly insulated.  The argument for the probe is that the infinitesimal amount of current that would flow to the ground is not harmful, while to sensitive species, the high potential voltage that builds up in an ungrounded tank can be.  I think of it as background noise, which does not bother some people, and drives others batty.> For the record, I do use GFI's on all equipment. <Excellent.  Without GFI's, there could be current associated with a probe, but with the GFI, if there were an actual insulation breach, it would trip.> I recently installed a controller (Lighthouse - http://www.mcuresearch.com < http://www.mcuresearch.com/> ).  The installation instructions start off by saying make sure to use a grounding probe to insure accurate probe readings (pH and ORP).   <Well there is your answer.  Although they may not be necessary for every tank, it sounds like you will be needing one to get your technology to behave.  Personally, I use them, ever since I measured the voltage (46 V!) and watched the reaction of the fish when installing the probe the first time.  They 'appeared' much calmer after the probe.> I would like a definitive answer on whether grounding probes should be used or not.   <This may always be a controversial topic.> Thank you very much, Jill. <Welcome. Alex>

Grounding Probes - 4/24/07 Alex, Thank you very much for your response.  I hooked up the grounding probe.  My probe readouts did not change after the addition - that is fine.   <That's good.  The readings could probably be affected for those tanks that had a significant voltage built up. <<Mmm, voltage does not "build up". RMF>>  After initially grounding mine, it took a long time for the voltage to return after removing the grounding probe.  It is very much dependent on the equipment installed, probably. I suspect my old lights were part of the problem.> Hopefully our inhabitants are happier now. <Maybe. Shouldn't hurt anyway.> Thanks,
Jill and Aaron.
<Welcome, Alex>

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: