stray voltage, how much is too much?

[okkiedokki]

I've been having some issues with my tank lately and one theory I have was maybe I just have a lot of stray voltage in my tank. I did a search and all I could find was how to use a voltmeter and not how much is too much.

Anyway here is what I have after I measured. With everything running I was at 4V or 5V. My 250 watt stealth heater was at 2V, my Maxijet 1200 pump I use as a return pump for my 50g was at 1V. Everything else was around or less then 0.5V.

Is that too much for a tank?

 

[cabrego]

If you get a grounding probe you will have no voltage. Anything you can feel is to much IMO, do you get zapped?

 

[okkiedokki]

I have never been zapped. I was just wondering because my tank issue is any store bought fish, or snail dies while any fish or snail i buy off a local reefer lives for a very long time.

My local fish store (best one in town) tested my water many many times and they says I have unusually pristine water in my tank so either it's stray voltage or some sort of disease.

 

[gabbagabbawill]

I would look for some other cause for your fish dying... still, you can get a ground probe, they are cheap. I think they are a must for a tank running a lot of equipment and would not go without one.

 

[Shablin]

I just had a heater go and cause a current in my tank; Id hate to think what would have happened without my grounding probe!

If you have stray current in your tank, corals dont open fully; All my Xenia, leathers fully closed and LPS, clams and worms were partly closed

If new additions are dying, Id test the water myself and look for other reasons why.

 

[MeReefBeef]

What is this stray voltage some of you reefers speak about? Sounds more like you're measuring a small bundle of static charge than "stray voltage". Also, voltage is not dangerous, its the amount of current. There can be thousands of voltage potential between two points, and as long as there is no current, no harm done.

 

[jdieck]

That level of voltage is not an issue at all. If you install a grounding probe insure your equipment is conected to GFCIs.

 

[Shablin]

error

 

[Shablin]

Of course all circuits should have GFIs, but please explain why you need a GFCI if you have a grounding probe. Wont the gfi just trip if there is a problem in the circuit? THe ground still goes to the same place the same way with or without a GFI right?? Id think (Im no expert) that if you dont have a GFI the ground would be more important. How does the GFI work (breaks the circuit to ground or something right??)


BTW my GFI never tripped but I couldn't feel any charge when my heater went (untill I put it in my DI bucket...)

 

[jdieck]

As in all of this posts I would state that anything I say shall not be construed as accurate even if it is and that you shall consult a licenced electrician as all cases have particular diferences and generalities may not apply.

The safe way is to have a functioning monthly tested GFCI and a ground probe.
A GFCI works by comparing the amount of current going in with the amount of current going out of the circuit. When it detects a difference it will assume that the current is leaking to ground and will trip with a difference of only 5 milliamps in just a few thousands of a second.
Usually given the materials of construction, an aquarium is insulated from ground so even with a GFCI (With no grounding probe) if there is a short to water it may not trip as current has no way to go to ground and create the unbalance necesary to trip the GFCI until you happen to touch the electrified water then you become the path to ground that makes the GFCI trip. If the GFCI is faulty you may be in trouble.
With the GFCI providing for a path to ground then the GFCI will trip saving you from the shock.

Without a GFCI IMO having a ground probe may have more risk involved than not having any.
See, the degree to which you are shocked depends on how well you are grounded when you close the circut to a live line or electrified conducting agent like salt water.
With a grounding probe there is a couple of potentialy very risky situations.
a) If you touch an electrified fixture (pump casing, metalic hood or reflector) while working in the water, because of the water will be perfectly grounded then the shock will be maximum with potential fatal consequences. Without a probe you will still be shocked but if you are lucky by not being perfectly grounded (wearing rubber sneakers, standing on a wooden ladder or wooden floor or on a dry floor) your shock may not be enough to kill you as if you were perfectly grounded.
b) If you have a probe and no GFCI and there is a short circuit with yout heater or any other submerged device, the breaker will not trip until the current is as high as 15 to 20 amps depending on the circuit. By the time the breaker trips there is a good chance that the short could have created a fire and the high current has killed everything in the tank and the shorted device released toxic chemicals from the burn (Oils, melted plastics, windings barnish and copper and copper sulfate)

Without the probe, a short circuit may shock you bad but as I mentioned may not kill you if you are lucky not to be perfectly grounded adn a short circuit may not generate a current high enough to trigger the breaker but still high enough for sparks to vreate a fire.

In summary, for safety sake, install probe and GFCI and insure the GFCI is operational by testing them at least once a month as unfortunately, GFCIs can become easily unreliable over time.

 

[jdieck]

<a href=showthread.php?s=&postid=15285176#post15285176 target=_blank>Originally posted</a> by Shablin
BTW my GFI never tripped but I couldn't feel any charge when my heater went (untill I put it in my DI bucket...#

There are several scenarios:
It is unlikely but possible that the short circuit in the heater went from neutral to hot #specially with no ground in the tank# so the GFCI did not detected a current difference between incoming and outgoing current so it did not trip.
It is also possible that the GFCI may have not been perfectly functional.

It could have been that you were not grounded when touched the aquarium water so you did not get a shock but you were partially grounded when touching the RO/DI. A thing to notice here is that pure water has a very high resistance so it can be considered non conductive #18 megohm) so I can say that your RO/DI might not be perfectly pure either.

It could also be that when moving the heater from the tank to the RO/DI a shift in the wire or internal electric components may have changed the nature and the characteristics of the short.

In any case it is good and I am glad it was a minor incident without serious consequences for you.

 

[gabbagabbawill]

<a href=showthread.php?s=&postid=15284980#post15284980 target=_blank>Originally posted</a> by MeReefBeef
voltage is not dangerous, its the amount of current. There can be thousands of voltage potential between two points, and as long as there is no current, no harm done.

I don't think that stray voltage should be trivialized like this... When was the last time you measured "current" in anything? Do you even know HOW to measure current?

Did you know that ventricular fibrillation in humans can happen with as low as 60 mA of current?

I think the OP's problem is something other than stray voltage; 4V is not enough to cause that much damage short term.

 

[okkiedokki]

Thanks for the replies everyone. I didn't really think that stray voltage was the problem, I just needed to verify that with everyone else. My corals look better then they ever have, same with my fish that I've either had for years or gotten from other reefers.

I'll have to work on a new theory on why my store bought fish and snails die overnight.

Edit:
Forgot to mention that yes my tank is hooked up to gfcis and I've tested them and they do pop with my tester.

 

[jdieck]

The one thing that keeps comming into my mind is acclimation. Many LFS maintain very low salinity in comparison with other reefers.

 

[okkiedokki]

As far as acclimation I've been floating the fish and snails for a half hour, then drip acclimating him in a bucket for an additional 2 hours. Then in the most recent cases, i've bought a mimic tang and a kole tang on seperate occasions and after they get put into my tank they go to town on my rocks. Then over night I see them laying on their side on the sand breathing very heavy with their mouth open.

I know my fish aren't attacking them because I removed them from the tank. And my LFS has tested my water multiple times and it's all come out very clean. We think their might be some sort of virus or something in my tank, so I'm now thinking of trying to keep my tank fishless for about two months and then try another fish after the two month period before i put my fish back in. If it is a virus then I'm thinking it will die out in two months without fish in the tank.

 

[jdieck]

But if it is a virus why you do not have issues with other reefer's fish? Also usually a virus will afect one species but why fish and snails and others?
It got to be environmental, in other words some kind of contamination then. Thisk of potential thinks we can not test for (Volatile organics and such)

 

[okkiedokki]

I was just under the assumption that the other fish have grown immune to it. Also, what's Thisk?

 

[jdieck]

<a href=showthread.php?s=&postid=15285991#post15285991 target=_blank>Originally posted</a> by okkiedokki
I was just under the assumption that the other fish have grown immune to it. Also, what's Thisk?

Fas fingers
I think I wanted to type Risk of potential things...

 

[MeReefBeef]

<a href=showthread.php?s=&postid=15285759#post15285759 target=_blank>Originally posted</a> by gabbagabbawill
I don't think that stray voltage should be trivialized like this... When was the last time you measured "current" in anything? Do you even know HOW to measure current?

No one has explained what the concept of stray voltage is to me yet =(

First off, if you're probing two random points in a fish tank, and measuring "stray voltage", this is highly inaccurate because of how easily resistance changes based on the shape of the medium. Essentially, just by moving the probes you would be changing voltage.

Measuring current requires an ammeter, attached in series to whatever you're trying to measure. In this case, you should not be able to measure any. If you end up measuring some, I supposed you could call it "stray current" and you would have a problem.

P.S. I just graduated with an Electrical Engineering degree with emphasis on electromagnetic theory.

 

[okkiedokki]

<a href=showthread.php?s=&postid=15286230#post15286230 target=_blank>Originally posted</a> by MeReefBeef
No one has explained what the concept of stray voltage is to me yet =(

First off, if you're probing two random points in a fish tank, and measuring "stray voltage", this is highly inaccurate because of how easily resistance changes based on the shape of the medium. Essentially, just by moving the probes you would be changing voltage.

Measuring current requires an ammeter, attached in series to whatever you're trying to measure. In this case, you should not be able to measure any. If you end up measuring some, I supposed you could call it "stray current" and you would have a problem.

P.S. I just graduated with an Electrical Engineering degree with emphasis on electromagnetic theory.

Well, i don't know much but from what I've read since we have mechanical equipment in our tank it will always produce some electricity in our tank. From the searching I did here I saw some discussion that the propellers from pumps will produce some minor amounts of electricity from the spinning it does in the water. From what I assume since it's low amounts of electricity in the gfci won't pop. Since the gfci measures changes in current and pops my guess is higher amperage and higher volts would make it pop. Now when I measured the voltage in my tank I used a voltmeter by putting the red probe in the water and the black probe in the ground of my gfci.

I hope I'm not wrong, maybe someone can chime in to verify if I am correct or correct me. I don't mean to lead anyone in the wrong direction.