- [Q] Do I need Voltage Lowering/Grounding Gadgets?
by booth-at-lvld.hp.com (George Booth) (1 Dec 1994)
- Re:Grounding electrodes
by mark.fisher/tpwd.state.tx.us (Wed, 18 Dec 96)
by booth-at-lvld.hp.com (George Booth)
Date: 1 Dec 1994
Matthew Swift (swift-at-bu.edu) wrote:
> I think your instinct is right and the grounding gadgets are a ridiculous
> fabricated need.
You may want to recheck your concepts before blathering away at something
you're quessing at.
> There is no way I can think of that a potential could be established between
> tank water and house ground.
That's not the problem. The EMF from various appliances generate eddy
currents in the fish themselves, causing distress. The lateral line
is a extremely sensitve organ and anything that distrubs it can stress
the fish and cause secondary problems. The EMF would generate a certain
potential in the fish due to its specific internal electrolite mix and
generate a different potential in the water. The difference between
the water potential and the internal potential is what causes the problem.
> And supposing there was some potential, the last thing you'd want to do is
> ground the tank, because potential equalizing itself is current, zap zap zap.
Guess again. The grounding probe "grounds" the water, putting it
at "0" potenial, which then effectively shields the fish from the EMF.
> Changing magnetic fields? I wouldn't suggest putting a magnetic fluorescent
> ballast right up to the water's surface, but those things are pretty well
> shielded, and I think any electrical disturbance would be negligible after the
> width of the bulb. Anyone experimented holding a copper wire on a meter next
> to a ballast? You are instructed to leave an inch or so between ballasts when
> mounting more than one.
What? The ballasts are enclosed by not magnetically shielded. You need
"mu-metal" for that.
> I think you should call up the maker of one of these $10 or $15 things
> and post what he/she says. It might be amusing.
Call Andrew Thomas at Sandpoint (503) 683-0600 and ask him about his
$45 Solution Ground probe. He has researched this problem with a
marine biologist at Stanford U. He may be amused at what *you* think.
Give us a report when you're done.
> Aren't they just a 50 cent piece of copper wire with some marketing attached?
You've clearly thought this through completely. No, they are titanium
wires so they won't corrode and contaminate the water (fresh or salt).
And you're not just paying an exorbitant markup on materials; there was
some serious money spent on research by Sandpoint to determine that EMF
was causing problems in the first place and how to solve the problem
in the second place. This cost must be recouped. And this this not
a "mass market" product due to flawed thinking such as you exhibit,
so they must charge appropriately more per item.
In my case, I had an adult discus that was showing signs of fin rot.
Adding a Solution Ground cured the fin rot and have generally calmed
Also, they used to jump when a light or appliance was turned on.
For instance, my wife would turn on the bedroom light and they
would shoot across the tank. They couldn't see the light, but they
somehow felt the effect of a minor current surge in the house. After
the Solution Ground was installed, this behavior has gone away.
I am not affiliated with Sandpoint. I'm just a satisfied customer.
BTW, if you call mention my name. I get "Frequent Buyer" credit.
George Booth "Nothing in the world is more dangerous
booth-at-hplvec.lvld.hp.com than sincere ignorance and conscientious
Freshwater Plant Tank Technology stupidity" - Martin Luther King, Jr.
Date: Wed, 18 Dec 96
I am a fisheries biologist, and in freshwater we use electrofishing
gear to collect fish--sending the appropriate current through the
water temporarily stuns fish and brings them to the surface, where
they are easily collected.
The following paragraph is from a reference, "Fisheries Techniques"
edited by Larry Nielsen and David Johnson, which may help to answer
the following APD posts:
>> The fish will have a very very low resistance, a lot lower than the
>Would you state for the record the actual resistance of the fish in
>question and the resistance of the water?
from page 150 of "Fisheries Techniques"...
"Because a fish has resistance, a given current density at one end
will result in a lowered density at the other, producing a voltage
gradient in the fish. Voltage gradients of 0.1 to 1.0 volts/cm are
most effective for stunning fish; these gradients can be maintained in
freshwaters of normal conductivity (100-500 micromhos/cm) by adjusting
circuit voltage to produce a current of 3-6 amperes. At high
conductivities, water becomes less resistive than fish and the current
tends to flow around them, resulting in little or no voltage effect;
this is the reason that electrofishing is not used in brackish or salt
water. At low conductivities (less than 100 micromhos/cm), the water
is more resistant than fish, but the electrical field is limited to
the immediate area of trhe electrode. When this occurs,a fish may not
be affected until it touches the electrode--then it suddenly receives
a high voltage gradient and dies".
It goes on to say distilled water has a conductivity of 0.5-4.0
micromhos/cm, most freshwater bodies are between 50-1,500 micromhos/cm
and saltwater is 500 times more conductive than freshwater.
From this discussion, it appears some aquaria have water more
conductive than the fish, while others are not, depending on the