Using ground probes in aquariums

Discussion in 'Reef Aquarium Discussion' started by Brew12, Oct 20, 2016.

  1. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Article Contributor Partner Member

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    A picture might explain this better.
    upload_2016-10-27_8-41-20.png

    In the US, we have one hot prong with the other prong tied to the neutral. The neutral is also tied to ground. In Europe, you have the exact same setup except you have both plug prongs tied to hot legs to get 240V (or 22oV). With both systems we still have around 120V to ground.

    Hope that helps explain it better.
     
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  2. locito277

    locito277 Well-Known Member

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    What would go where?
     
  3. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Article Contributor Partner Member

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    The probe end goes in your sump. The plug goes into any wall outlet. The ring terminal is optional for most installations.
     
  4. Gravityreefing

    Gravityreefing Well-Known Member

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    I just ordered one.. hey the piece of mind of not ever getting shocked.
     
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  5. jasonrusso

    jasonrusso Well-Known Member

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    That's what I said also. Then I found that my circulator was leaking. Maybe the best (safest) $12 I've spent.
     
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  6. Gravityreefing

    Gravityreefing Well-Known Member

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    Safe n more Safe is what I say.
     
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  7. Blue Earth Aquariums

    Blue Earth Aquariums Member R2R Supporter

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    I definitely recommend them especially on older systems
     
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  8. akarusso

    akarusso Well-Known Member R2R Supporter

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    Could not agree more
     
  9. Lasse

    Lasse Well-Known Member R2R Supporter R2R Excellence Award

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    First – Electrical chock from aquariums is a serious problem. It’s a matter of life and dead. But I´m not sure that a grounding probe is the best solution over all. My concerns is based on the same facts as @skim ´s post 67. And I do not – at the moment – agree with post 68. For me – if you have 240 V from a leaking heather or pump at one point in the aquarium and 0 V (the ground probe) in another point – the field difference is 240 V not 1 V. Either – I do not agree with OP that saltwater fishes not will be unaffected of differences in the field potential. There is some evidence that they have sensors that use this for information

    My solution of the problem is to use 24 V DC device as much as possible (circulation pumps and wave makers) and to use a titan heather – in Europe they are grounded by them self – and as normal in modern Swedish electrical installations – a residual current devices at 30 mA.

    However there is some problems with leaking 24 v DC devices – they can give some different potentials in the water (compared with the main measurement unit – the aquarium computer) and therefore create small currents that will interact with electrode measurements like pH, redox and salinity.

    My solution to this is to have my titanium heather (grounded) in the sump and also have my electronical measuring equipment at the same place. Most people also try to have their heather on an own residual current devices.

    Sincerely Lasse
     
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  10. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Article Contributor Partner Member

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    Lasse, you are correct, the field difference is 240V. However, if you have a ground probe, the majority of the voltage will drop across the point of the fault in the equipment, not in the water.

    The effective resistance of sea water is roughly 0.2 ohms per meter. If your ground probe is 1 meter from your faulted equipment it would take 5 amps of current through the water to create a 1V drop. The other 239V would be dropped at the point of the fault. My heaters are within 0.3 meters of my ground probe so it would take 15 amps of fault current to get a 1V drop across the water itself. (Yes, I oversimplified the math, but the results are nearly the same using the actual equations. It is just Kirchhoff's voltage law in action)

    I respectfully request you read my post 68 again. I state that saltwater fish are most definitely impacted by differences in the field potential. They are only not "shocked" in the same way we are.

    I believe using DC devices is an excellent recommendation. I also think it is a great reason to use Vortech powerheads such that the electrical motor is not in the aquarium itself.
    If you are using a titanium heater that is grounded, you have no need to use a ground probe. The titanium heater tube, connected to a ground wire, connects to your house ground. This is exactly how most ground probes are constructed. You just found one with dual functionality ;)

    Lasse, thank you for continuing the conversation!
     
  11. Lasse

    Lasse Well-Known Member R2R Supporter R2R Excellence Award

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    I´m sorry that I jumped in late - I missed the thread before.

    Most upset I get over the fact that it is still allowed to sell and use heaters made of glass and with the the electronics in the heater. Its no question if they are going to be broken - the question is when.

    That’s true – because they are not grounded. If they touch or rest at a grounded device – it’s another question.

    In post 68 – I think that you are wrong according how electro- fishing works. What I have learned is that the differences in field potential make the fishes to actively swim to the point with highest potential and they will be paralyzed near this point – in best cases. What I have seen in the practical field confirms this. The fishes come up just in front of you – all fishes that’s inside the electrical field you create but you have to be fast with the net – the chock is only temporally and very weak - many fishes pass by you if you not is a fast netter. Some fish coming in a high speed. I can surly certify - if a rainbow trout of 1 kilo comes from 20 meters in full speed (during electro-fishing), decide to jump 1 meter in front of you in order to escape from this annoying electric environment and hit you at the shoulder – it hurts.

    I´m either not sure that your explanation why electro-fishing not works in saltwater is right. Normally it does not work in freshwater lakes either – at least what I know it works best in smaller streams where the fishes have no chance to avoid the electrical fields through swimming to the side. And – at least here – we always fish in the direction of the stream – in the other way – the stream help the fish to pass you – I think. I´m sure that electro-fishing works with saltwater also if there was saltwater streams – maybe I shorter distances – but I think it will works nearly in the same way (from a biological point of view).

    As you understand – I more concerned about creating electrical fields with different potential in the display tank compared with other things. With a separate ground probe in the display tank – you will create electrical fields even in saltwater.

    And it’s wrong that there is no problems with electrical shocks in freshwater. It’s the same. If there is a higher potential (>0) in the aquarium – if you ground it with your hand or with a probe – it will run current trough the grounded point – and if that point is you – there is some problems if the potential is high enough.

    My advices are.

    Use 24 V DC devices – at least in the display tank. If you use a heather – use a grounded titanium heater without internal electronic. Place your measurement equipment at the same part of your system (as the grounded heather). Place all this in the sump if you can. Use a residual current devices at 30 mA – a separate device for the heather is best.

    A residual current devices at 30 mA is the most important device (IMO) - and a grounded heather. Salt or fresh water - it does not matter.

    Sincerely Lasse
     
    Last edited: Jan 8, 2017
  12. Lasse

    Lasse Well-Known Member R2R Supporter R2R Excellence Award

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    I should have done a Google before last post :) Instead of relying on my memory based on information I got from my education back in the 80:ties. :) On the other hand - I have an old mans memmory - very good for things happens the last 20 secounds or for 20 years ago :) bad between :)

    There is equipment for lake Electro-fishing. I have never heard about them in Sweden - therefore i did not know about them. Se this. The article comfirm what I wrote aboute how it works. The reason why its not works so good in saltwater is that salinity influences the shape and extent of the electric field.

    However – I´m still a little bit concerned about an other thing that can happens if you have currents in saltwater. (if you ground – you will have currents if you get potential differences by leaking products) – electrolyse and forming of chlorine gas. Someone with background in the electro-chemical industry may help us out here.

    Sincerely Lasse
     
    Last edited: Jan 8, 2017
  13. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Article Contributor Partner Member

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    Since you use a heater that is the same as a ground probe your Saltwater fish are effectively grounded. To ground something, you connect a conductor from that object to an earth ground. Since saltwater is very conductive, it acts like that conductor which grounds the fish. Of course, since the fish is an insulator compared to the water around it, the grounding is less relevant.

    As long as we use any electrical equipment in our aquariums we will always be creating electrical fields within it. Even low voltage DC pumps will induce voltages (via magnetic fields) in our tanks. If I remove my grounding probe I can change the voltage reading from my aquarium to ground by raising and lowering the speed of my Vortech MP40's. It is important to remember that brushless DC motors don't really run on DC. They run on AC. It is only the shape of the wave that is different. The controllers for DC motors tend to produce a square or trapezoidal wave form instead of a sine wave.
    A ground probe would be relatively useless in a fresh water aquarium unless you had really dirty or brackish water. Typical fresh water has a resistance of well over 2,000 ohms per meter compared to 0.2 ohms per meter for seawater. As an oversimplification that will get you in the ballpark, use ohms law. Voltage = current x resistance. If you have a 240V wire exposed in freshwater and a ground source 1 meter away you would have 0.12 amps of current flow. That same fault in saltwater would cause 1200A of current flow.
    The difference between a fatal electrical shock and not feeling anything is typically only a few hundred ohms. In a fresh water system you only need to be a few inches from the fault to get the extra resistance you need. In saltwater, you would need to be several meters from the fault to get any benefit from the resistance of the water. To really get the benefit of a ground probe in a fresh water aquarium you would need to have one by every component.

    The output of an electrofishing unit needs to be adjusted for the conductivity of the water it is used in. At some point, the water becomes to conductive when compared to the resistance of the fish for it to work.
    http://myfwc.com/research/freshwater/resources/techniques/electrofishing-faq/ is the Florida Wildlife Conservation Commission website which talks about electrofishing. Here is the key statement.
    "Can you use an electrofishing boat in saltwater?
    No. The conductivity of saltwater is higher than the conductivity of the fish. In saltwater, the electricity goes around the fish instead of through it, rendering this technique ineffective for fish collection."

    To get efficient electrolysis you would typically use DC although it will occur in AC.
    I am curious, do you see bubble formation on your heater since it is a ground probe? I doubt many aquariums have enough current to cause significant amounts of electrolysis.
     
  14. MacQac

    MacQac Well-Known Member

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    I'm a new reefer and just purchased one based on the advice here. Keep sharing, you never know who's reading/ watching and for every one that posts, like me, there are certainly more who take the advice and do not post. Thank you!
     
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  15. Lasse

    Lasse Well-Known Member R2R Supporter R2R Excellence Award

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    I do not think that this statement is completely right – neither is my statement about that only field potential is important (voltage) completely right. The importance with discussions like this is that you will be forced to update your knowledge. I found this article that explain it in a good way. Yes – it’s possible to electro-fish in high conductive water like saltwater – its a matter of power – not only voltage or current. That article also strengthen my unwillingness to have electrical fields (and current) there my fishes is.

    I did not argue if a ground probe works in freshwater or not - only that 240 V AC (as we have in Sweden) in the water will harm you if you put your hand in it and probably kill you. It has happen. But if the ground probe take down the voltage from 240 to 40 V AC - there is less chans to get killed for sure. Combine this with a residual current devices at 30 mA - you will break the Circuit Before it harm you or your fishes. If you ground (in fresh or saltwater) - do the combination!

    To use a grounded titan heather is the best way I think - because you will have the ground very close to the fault.

    No – I do not see any bubbles from my heather but it was more a theoretical question – if we move against using 24 DC equipment in our tanks – how likely is it that you get electrolysis if there is a leakage of current (between a plus and minus in worst case or between plus and the ground probe in the other case) I do not know – therefore the question.

    Sincerely Lasse
     
  16. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Article Contributor Partner Member

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    First, let me start by saying I have thoroughly enjoyed this conversation! I really appreciate your insight. I also learn things every time I am challenged which is a fantastic thing for me.

    I think this article is excellent in some ways. What it shows is that you need a voltage drop across the fish to cause the correct amount of current to flow through the fish. I do find it to be a bit misleading though. When it talks about "highly conductive water" it must be referring to highly conductive fresh water. While the resistivity of seawater does vary substantially with different salinity levels and temperature, it is generally between 35,000 microSiemens/cm and 60,ooo microSiemens/cm. Notice that the graphs on these pages end at 800 microSiemens/cm. I believe the conductivity of a fish is estimated at a little over 100 microSiemens/cm. We often say current takes the path of least resistance but in reality it takes all paths of resistance in proportion. So while I will agree that it is technically possible to electrofish in saltwater, you will find it would take so much current to get the necessary voltage drop across the fish that the heat (I2R) would cook them.

    One thing I would like you to think about. We think of the saltwater within our aquariums to be very uniform. In some ways, it is. In reality, we have different flow rates, temperatures, and densities within our systems. These will all make the water more or less conductive. If these differing voltages within the water occur next to the fish, I believe it can cause irritations to it's sensors. In my opinion, the best way to prevent this from happening is to remove all voltages from the tank as possible. I do this with a ground probe. In theory, the lower the voltage in the water, the smaller the difference in these fluctuations should be.

    That is an excellent point. I should state that it is much less effective in fresh water. It can still serve a purpose but may not protect you if you have a fault too far from the probe. I will make sure I do that in the future.

    I actually agree with this since the heater is the most likely failure point. I think I would still use a separate grounding probe just for peace of mind.

    Again, your 24V DC equipment is actually using an AC wave to the motor so it will work almost exactly like AC. In reality, electrolysis is possible in our aquariums but only during a fault with 2 exposed electrodes. The amount of gas generated would be fairly negligible due to the low currents involved. (I'm fairly familiar with electrolysis since I was certified to work on my submarines oxygen generators which operated using electrolysis. Granted, that was many years ago.)
     
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  17. Lasse

    Lasse Well-Known Member R2R Supporter R2R Excellence Award

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    These varations accours also in the wild - I think that the fishes has adapted to this. The problem fo me is that you have 0 V at the grounded part and another potential at the "leaking" point. Even if the potential drop very fast - you will have a current going to ground.

    And I did not say that it could be practical to Electro-fish in saltwater - only that its possible in a teoretical way :). But the important thing is that the article show that fishes will be affected in som way or another in high salinity waters - even if the method do not give a good undrestanding of the size of the population.

    Sincerely Lasse
     
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  18. hart24601

    hart24601 Well-Known Member

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    So are finnex titanium heaters grounded and do the same as a probe?
     
  19. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Article Contributor Partner Member

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    I believe so, yes, although I haven't cut one apart to verify it. Since they do have a ground prong, the only thing that makes sense is for it to connect to the titanium housing. That makes it exactly like putting a heating element inside a ground probe.
     
  20. jgvergo

    jgvergo Well-Known Member

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    Thank you! I simply never knew about grounding plugs. I just placed an order and will install it tomorrow!
     
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