STN and Stray Voltage

[James404]

So I have had a bunch of STN lately on some of my acros, some started at the tips, some near the base. I first attributed it to starting to run ROX carbon, which I have stopped using. I decided to test for stray voltage tonight and was surprised to see a measurement of about 30V. I started the unplug routine and it appears to be coming from multiple items. What are your guys thoughts on if this is the culprit of STN?

I have been researching and seeing a lot of mixed opinions on the subject and items such as grounding probes. I was kind of leaning toward installing one.

 

[MammothReefer]

I install them w/gfids. I had a TON of problems with my old system due to stray volts and I couldn't figure it out for the life of me. Fixed the problem montis came back, acros were keep able again. ..fsk&ng pos finnex heaters. Months of fighting w/the tank.

 

[James404]

Yea I think I am definitely picking one up tomorrow, I run everything on GFI as well.

 

[rodneyri]

how do you test for stray voltage? and what is GFI

 

[DNA]

I find the lack of ground fault devices in the US astounding.
Where I'm from at least 99.9% of households have it.

Voltage is one thing but is there any current to go with it?

 

[James404]

You can use a multimeter set on AC voltage, one probe goes in the water, one goes to ground. If the meter picks up anything you have stray voltage.

GFI is ground fault interrupt, it's the type of outlet you typically see in kitchens and bathrooms with the test and reset buttons.

 

[sowellj]

You will get widely varied opinions on this. As someone earler mentioned it, stray voltage is quite different than stray current. For example, assume you do have stray voltage. If you place your hand in the tank and are wearing rubber soled shoes, you will not feel a shock. If you take your shoes off, or provide another route to ground, you will get a shock as the current now has a path. I just don't see how corals are 'aware' of stray voltage. Stray current is another beast. My opinion (just opinion) is that stray voltage (not current) is a bit of reefing urban myth.

 

[preef]

http://www.reefcentral.com/forums/showthread.php?t=1993937

 

[MammothReefer]

Myth? I have a bucket of dead corals due to a blown out titanium heater that was electrocuting my tank for months until I found the source of the problem. I found out when I grounded my elbow to my lumenarc while pulling my hand out of the tank and went flying. I went threw every piece of equipment until I found the busted heater (I was running 4 heaters at the time..500g w/sump in the garage). Once found and removed everything came back around.

 

[ReeferBill]

Stray voltage?

Stray voltage?

I was thinking about addind a grounding probe because if my nails are cut to short I can feel the electricity in those areas that are newly cut. Last night I overflowed a gallon of RO water and the water on the counter shorted out band melted the switch for my garbage disposal and kitchen cabinate lighting switch. I took out the melted switches and now I have bear wire hanging next to my display tank and between the kitchen sink . Do I need to replace the wiring or can I just tape them with electricl tape and replace the double switch next to the GFI?:blown:

 

[preef]

I have no doubt that broken electrical equipment will cause issues. I was in fact shocked by my Stealth heater by sticking my hand in the tank. I was talking about small amounts of current induced by perfectly good pumps, lights, etc...

Here's my quote from the other thread:

Always use a GFCI and ground probe are for your safety. I have never had a GFCI trip for no reason. Using a GFCI will protect you and your tank from a broken piece of equipment (think stealth heater) if one were to fail.

I have yet to see any study or conclusive evidence that small amounts of stray current will cause a problem. For some reason everybody likes to blame issues they can't solve on stray current/voltage. Pumps, powerheads and lights will generate magnetic and electrical fields that will induce some current in the tank even if the seals have not been compromised.

If you have a broken heater you are also leaching copper and who knows what else into your tank water.

 

[preef]

I was thinking about addind a grounding probe because if my nails are cut to short I can feel the electricity in those areas that are newly cut. Last night I overflowed a gallon of RO water and the water on the counter shorted out band melted the switch for my garbage disposal and kitchen cabinate lighting switch. I took out the melted switches and now I have bear wire hanging next to my display tank and between the kitchen sink . Do I need to replace the wiring or can I just tape them with electricl tape and replace the double switch next to the GFI?:blown:

Yes. Add a GFCI and a ground probe for your safety. If you are getting shocked you have a major issue that needs to get solved ASAP. Start with your heater. Unplug it and see if you still feel the tingling.

I don't understand the second issue. You should call an electrician for that one.

 

[ReeferBill]

Stn and Stray Voltage ?????

Stn and Stray Voltage ?????

Thak You Preef ; Can I just replace my melted burned up charcoal switches on my garbage disposal and cabinate switch next to reef tank?:hammer:

 

[ccLansman]

I had an issue with loosing fish due to a 30V stray voltage as well. Added a grounding probe and have never had an issue since.

 

[preef]

Thak You Preef ; Can I just replace my melted burned up charcoal switches on my garbage disposal and cabinate switch next to reef tank?:hammer:

Not sure. You should really call an electrician. A switch should never burn up before the circuit breaker trips. You might have more sever issues there.

Maybe you should also add "and electrician" to your signature.

 

[preef]

I had an issue with loosing fish due to a 30V stray voltage as well. Added a grounding probe and have never had an issue since.

How do you know the fish died from 30 V of stray voltage? Just because you had 30V of stray voltage in the tank with respect to your home's earth ground doesn't mean that it killed the fish. It's also impossible to prove a negative. You don't know what the outcome would have been had you not added the probe.

Don't get me wrong. I'm a strong believer in ground probes.

 

[James404]

I've read most of the threads around here regarding stray voltage, and I think you are probably right that induced voltage from equipment functioning correctly is harmless. I kind of just look at it as one more possible thing to rule out in my troubles. I added the ground probe and now measure 0V so I guess we'll see.

 

[preef]

When I first ran carbon in a reactor I had a lot of STN and RTN. That would be my guess. Too much too fast.

Regarding the induced voltage. Here's an experiment you can try.

1. Remove your ground probe.
2. For those with with Vortechs: Measure AC voltage from your tank water to earth ground with the pump on and off. Since the the dry side is completely isolated the increase in voltage you see is 100% due to induction into the tank. This is the same induction that makes the impeller on the wet side spin.
2. For those with Koralias: Pull the powerhead out of the tank and hang it on the dry side of your glass. Turn the pump on and off and you'll see the voltage change. You can also put the pump in a large plastic bag and dip it in the tank. Measure the voltage with the pump on and off. In my tank I see about a 5V increase in tank voltage when a Koralia is ruened on.
3. Before replacing the ground probe measure the current between the tank water and the probe. It should be very low. In my case I measure about 1 microAmp. Anything much higher than that may mean you have faulty insulation some place in your system.
4. Replace the ground probe.

With my ground probe out of the tank I measure about 20 VAC between my tank water and earth ground. Everything contributes to it. No one thing completely gets it down to 0. Even my T5s induce about 0.5V. My twisty CF bulb for my fuge also adds about 0.5V. This is because current from anything inside or outside the tank will induce current/voltage in the tank. Any current generated should be extremely low provided your insulation is intact. The ground probe simply references the tank voltage, which will normally be completely isolated, to earth ground. I hope this makes sense.

 

[James404]

When I first ran carbon in a reactor I had a lot of STN and RTN. That would be my guess. Too much too fast.

Regarding the induced voltage. Here's an experiment you can try.

1. Remove your ground probe.
2. For those with with Vortechs: Measure AC voltage from your tank water to earth ground with the pump on and off. Since the the dry side is completely isolated the increase in voltage you see is 100% due to induction into the tank. This is the same induction that makes the impeller on the wet side spin.
2. For those with Koralias: Pull the powerhead out of the tank and hang it on the dry side of your glass. Turn the pump on and off and you'll see the voltage change. You can also put the pump in a large plastic bag and dip it in the tank. Measure the voltage with the pump on and off. In my tank I see about a 5V increase in tank voltage when a Koralia is ruened on.
3. Before replacing the ground probe measure the current between the tank water and the probe. It should be very low. In my case I measure about 1 microAmp. Anything much higher than that may mean you have faulty insulation some place in your system.
4. Replace the ground probe.

With my ground probe out of the tank I measure about 20 VAC between my tank water and earth ground. Everything contributes to it. No one thing completely gets it down to 0. Even my T5s induce about 0.5V. My twisty CF bulb for my fuge also adds about 0.5V. This is because current from anything inside or outside the tank will induce current/voltage in the tank. Any current generated should be extremely low provided your insulation is intact. The ground probe simply references the tank voltage, which will normally be completely isolated, to earth ground. I hope this makes sense.

Great post Preef and that is exactly what I was seeing, each item was inducing some current, wasn't one thing in particular. I will keep the probe just for the piece of mind but I am fairly certain my issue was too much carbon.

 

[MammothReefer]

Why would my titanium heater leach copper? It's just a coil in a tube.