Quoted from another source
"Everything I have learned in this hobby over time makes sense in some context. The use of a grounding probe, however, makes no scientific sense at all in any context. The use of a grounding probe is to bleed off stray voltage in one's water column, which purportedly, is an undesirable thing. Grounding probes perform this by introducing a ground level potential into your water column which effectively "grounds out" your entire system.
My contention is that elevated voltage levels pose no harm whatsoever to the inhabitants of one's tank. Voltage potential is a relative phenomenon, in most cases, relative to "true ground" or that of mother earth. A living organism cannot sense in any way if the voltage potential of their body is different from that of true ground. Only when they come in contact, and become a conduit between an elevated voltage potential and that of a lesser potential or true ground, do living organisms sense any discomfort due to the electrical current generated by the flow of electricity. To illustrate my point, think of the bird on a high voltage power line example. Only when the bird grounds out or touches something of significantly lower voltage does he experience any sensation of discomfort that could ultimately kill him. The electrical current running through his body is what he senses (and likely dies from, if great enough) between the two differing voltages, not the voltage itself.
Grounding probes are one of the greatest marketing scams in this hobby, and one of the most pervasive, and here is why. Grounding probes provide an electrical conduit for electrical current to begin flowing between the source of an elevated voltage and that of the grounding probe. This is how they effectively "ground" your water column. The flow of electrical current, itself, between a contributing source and the grouding probe causes discomfort to all things that do NOT present a greater resistance to ground than that of the grounding probe. This means any organism that is not grounded (viz., your fish, etc) will suffer electrical current flow over/through their bodies if they orient themselves between the contributing source of voltage and your grounding probe.
I would agree, that from a personal safety point of view, a grounding probe seems like a good idea. From the tank inhabitant's perspective, however, grounding probes significantly increase electrical current flow. Unfortunately, the two objectives are really in conflict with each other. Hopefully, we all understand that electricity will take the least path of resistance. You, the human, outside the tank are ultimately grounded and present greater resistance than that of the grounding probe, which results in no electrical current flow over/through your body. GFI protected receptacles ARE A MUST and are the only means to truly protect oneself, not via a grounding probe.
As many people know, there are two broad classifications of circuit failure. Circuit shorting (to ground) and an open circuit where power supplied to the device no longer makes its way to ground through the device, resulting in the device itself and any conductive medium to which it is attached (water, in this case) will float to a difference in potential from ground. Both types of failure will result in a noticable decrease in performance and ultimate failure of the device.
Without a grounding probe in place, when a device begins to short, the stray current produced will remain local to the device, as electricity will always take the path of least resistance. The proximity in the difference of potential between the input side and output side of the device is what accommodates this least path of resistance. By definition, shorts in electrical circuits are always found somewhere prior to the intended output, and as such, incur some level of impedence to complete the circuit. Grounding probes twart this remaining device impedence by offering a lesser path of resistance (only the distance between the device and probe over a conductive medium -- water ), resulting in electrical current flow external to the device.
My conclusion: From the human perspective, adding a ground probe results in the impossibility of sensing any electrical shock whatsoever, due to the electrical current's preferential path of going through the grounding probe as opposed to the human's body to reach ground. Any part of the human body presents too much resistance over that of the water to sense any shocking effect. From the fish's perspective, however, they are not grounded. In fact, their bodies are likely more preferential conductors than saltwater due to less salt contained within their tissues (the less impurities in water, the better conductive property it has, for reasons in my earlier post). Fish do, however, have the ability to minimize their exposure to the (increased) voltage gradient created by adding the grounding probe; either by swimming out of the area containing maximum gradient or by orienting their bodies to be perpendicular to the field, thereby minimizing their bodies "span" within that gradient.
....[continued next post]
