What Causes Stray Voltage And How To I Get Rid Of It?

[Dr. Bogger]

I have been reading (specificly from Wilder) about this stray voltage that can get in the tank water... i want to understand more about this...

What causes stray voltage? how do i get rid of it? anymore info about it?

 

[Sammie7]

Don't know much about the subject, but I googled it. I think it is generally more of a cause of concern for marine aquariums. Not to say that you shouldn't also be cautious with freshwater tanks.
http/www.reefs.org/library/aquarium_net/996/996_5.html
http/www.netpets.org/fish/reference/reefref/grounding.html
http/www.farmertodd.com/library/rkessent...electricity.asp

 

[dogfood]

Salt water is more conductive to electricity so it's more of a concern. For FW a grounding probe is necessary.

 

[andywg]

The stray voltage is small amounts of voltage that can occur in the tank introduced by various electrical objects in or near the tank (powerheads, filter pumps, florescent lights etc).

The most common believed cause is powerheads, which becomes more of a problem in marine tanks as they tend to have far more powerheads in them. As mentioned above salt water conducts electricity better.

For the only piece of research I have found try here: http/www.reefs.org/library/aquarium_net/1298/1298_3.html

Again note that the only concern is for SW. I have never seen anything remotely like scientific literature debating the affects of electricity in a FW tank, and it is only ever considered a requisite in tanks containing sharks due to their Ampullae of Lorenzini pores the sharks use to detect electrical signals and fields from prey.

 

[WILDER]

The only thing I know about stray voltage is that is can cause a bent spine in fish.

 

[Dr. Bogger]

Now what if i add salt to a fresh water aquarium... would that mean it is prone to stray voltage also?

 

[voo]

What about brackish tanks?

 

[WILDER]

A question for andywg he very intelligent on the science side.

 

[InaneCathode]

Now what if i add salt to a fresh water aquarium... would that mean it is prone to stray voltage also?

Well, a salt solution conducts electricity better than pure water. I'd imagine, yes it would be more prone to stray voltage.

 

[andywg]

Now what if i add salt to a fresh water aquarium... would that mean it is prone to stray voltage also?

It would expect it depends on what sort of salt is being added.

If you are adding just aquarium (otherwise known as table) salt then there may be a different response than with marine salt which contains a large number of other salts and electrolytes. Pure water is classed as a poor conducter whereas Sea Water is a good conducter. Sea water is almost as close to copper for electrical conductivity as pure water is to rubber.

If you are adding salt as a tonic (and here the first question should be why) then I doubt you will be putting enough into the water to have a siginifcant effect on the nature of the water. I would expect brackish tanks to behave as a percentage of Sea Water, so half strength brackish would half as succeptible to any problems. This may be far from correct, however.

I would not worry about this unduly unless you have a shark tank as these are the fish that really suffer from stray voltage. If you are the type to worry then just throw a grounding probe in, it should deal with any of the stray voltage.

One of the most worrying things from the research above is how an old powerhead can cause voltage to appear in the tank with just a piece of the plastic casing touching the water, indicating that the plastic has somehow become a conducter. This, in my mind, makes Tunze Stream powerheads seem far better as they run on a far lower DC voltage (12 or 24V) compared to mains powered powerheads running at 110 or 230V.

 

[raptorrex]

Now what if i add salt to a fresh water aquarium... would that mean it is prone to stray voltage also?

It would expect it depends on what sort of salt is being added.

One of the most worrying things from the research above is how an old powerhead can cause voltage to appear in the tank with just a piece of the plastic casing touching the water, indicating that the plastic has somehow become a conducter. This, in my mind, makes Tunze Stream powerheads seem far better as they run on a far lower DC voltage (12 or 24V) compared to mains powered powerheads running at 110 or 230V.

worrying indeed! could it be something to do with the magnetic field used to turn the impeller, as the unit gets older?

 

[andywg]

worrying indeed! could it be something to do with the magnetic field used to turn the impeller, as the unit gets older?

While the electromagnetic field is almost certainly the starting point for the voltage, this does not explain why the plastic casing (used for its electrical insulation properties) should change and seem to be a conduit for the eletrical energy.

 

[raptorrex]

worrying indeed! could it be something to do with the magnetic field used to turn the impeller, as the unit gets older?

While the electromagnetic field is almost certainly the starting point for the voltage, this does not explain why the plastic casing (used for its electrical insulation properties) should change and seem to be a conduit for the eletrical energy.

yep just wondering if the field may extend around the pump, giving the impression, that the case is live?

 

[andywg]

yep just wondering if the field may extend around the pump, giving the impression, that the case is live?

I would be surprised as the magnetic field would need the internals of the motor in order to generate an electric field. I do not think that the magnetic field could extend outside as a magnetic field and then show up as electricity on a voltage probe or osciliscope.

 

[Bignose]

It would expect it depends on what sort of salt is being added.

While it would depend on what salt is added, the conductance of the water will be a much stronger function of the concentration of salt. That is, the difference between 1 mole/L of NaCl and 1 mole/L of KCl will be much, much less than the difference between 1 mole/L of NaCl and 2 mole/L of NaCl.

Part of the issue with old plastics is that they change properties dramatically. I am just going to guess here, so I really don't know, but as ions from the water gets trapped in the plastic, the previously resistant plastic may become more conductant. Kind of like a metal, where the atoms line up and can pass electrons, the ions trapped in plastic matrix may be performing the same function. I do know that some plastics age poorly -- look at all the brittle bakelite fixtures that are out there now, when they were new they were strong and ductile and sturdy, but now it seems like you almost only have to tap them to shatter it. As another example, PVC left outside for a few years becomes very brittle also, even though it is pretty dent-resistant when new.

The magnetic/electric (you can't have one without the other if electrons are moving, and electrons are moving if the unti is on) field would drop off as distance squared away from the source. That is, if the field is x strong 1 cm away, it would be x/4 2 cm away and drops off rapidly like that.

I think that the biggest thing that these units have been made pretty safely, I doubt that a company could make too many unsafe units and not be sued into bankruptcy. But, if you ever feel a tingle around them, I know that I would be pitching that unit ASAP... after unplugging obviously!