Grounding Your Fish Tank

[bbyatv]

I have found a funny thing.

 

If I have a small cut on my finger and stick it in my tank it stings like heck.

 

If I take a glass of water out of the tank and then stick my finger in it, no sting?

 

Am I creating a bunch of static electricity by running the water through the PVC?

 

I have no pumps or other electrical devices in the water that might be causing this electrical sting.

 

Any ideas? Has anyone else experienced this?

 

Should I add some sort of a ground wire from the tank water to a ground in the house?

 

Bruce

[jamesbuf]

I experience the same thing if I don't have my grounding probe in the tank.

[Almon]

No pumps, heaters, or any electrical devices in the water? Really? What about your lights, or their housing touching water or touching something else that is touching water. There is obviously some electrical potential in the tank.

[bbyatv]

I think the electrical potential is generated from the water moving through the PVC.

 

Notheing else touching the water?

 

I wonder if this potential is at all harming the corals? Probably not if they are not grounded?

 

Bruce

 

No pumps, heaters, or any electrical devices in the water? Really? What about your lights, or their housing touching water or touching something else that is touching water. There is obviously some electrical potential in the tank.

[bbyatv]

Here is an interesting article on ground probes.

 

I may not want one.

 

http://angel-strike.com/aquarium/GroundingProbes.html

 

Bruce

[steveoutlaw]

It could be coming from something that's in your sump. If there is current leaking from one of the devices in your sump it can easily be transferred to your main tank via the return water.

[Origami]

If it's not leaky electrical equipment (like a cracked pump housing or heater), it is very possible that it's static charge being built up by water or even by the motion of a pump impeller in it's housing. You may be able to identify the culprit by shutting everything down then watching (or feeling) for a change as you bring things back up one by one.

Edited September 12, 2008 by Origami2547

[bshriver]

If you have stray voltage from a device leaking into your tank, plugging the device into a GFCI extension cord should identify it - especially if you use a grounding probe while running the test. The GFCI should trip when the device is plugged in. You could test every submerged device one at a time to see which ones trips the device.

[treesprite]

I get a tiny static electricity shock if I touch the 16g's pc fixture, which is metal, with wet hand when the lights are on. That tank has a glass cover, so I don't worry about it. One time I thought there was a problem with the 65g - I tested everything in the tank, found nothing, then realized it was my carpal tunnel syndrome reacting to the way I was reaching my hand.

Edited September 12, 2008 by treesprite

[Black Mammoth]

You aren't feeling static electricity generated by PVC. You have something "leaking voltage." If you are "leaking voltage" you may not trip a GFCI. There are several variables involved. You have a pump, heater, powerhead, etc. The easiest way to detect it is to turn off each device one by one until it goes away. Lights will only cause it if there is a direct connection somehow, meaning it isn't the visible light causing the problem. That probably isn't the cause either. The "leakage" needed would most likely be pretty high and you would have noticed it by now

 

I only skimmed the article about the grounding probes. But electricity is relatively simple. It WILL seek ground. The grounding probe is good because the voltage will go to ground to complete the circuit (path). If the grounding probe was absent, it would "float" around looking for ground. Voltage WILL go to ground one way another. It might be through the path from the tank to the stand to ground....or it may seek another electrical device.

 

Cliff Notes: You have something causing the stray voltage and grounding probes are good. Find the source and fix the problem. Eventually it will get bad enough that it may very well trip the GFCI.

[treesprite]

I have a grounding probe, but am not using it because of the controversy over use.

[bbyatv]

I just stuck my finger in my sump and no zap. I still get a zap in the main tank. All the lights are off in the main tank. I have no power heads in the main tank. Maybe it is the chiller? I will try to unplug one item at a time and see when it goes away.

 

Bruce

[Coral Hind]

Black Mammoth is right on.

 

Typically a GFCI will trip in 25 ms or so at fault currents exceeding 20 to 30mA, they are permitted by UL to take several seconds to trip at fault currents in the 6mA range. Current entering the hand has a threshold of perception of about 5 to 10 mA (milliampere) for DC and about 1 to 10 mA for AC at 60 Hz. So yes you could feel it and not have the GFCI trip.

 

The good thing is your heart does not normally fibrillate until currents reach about 60 mA.

[bbyatv]

Given that I do not get a zap on my finger in the refugium and the lights are off, it comes down to one of three things that contact the water outside of the refugium.

 

1. A Mag 12 pump mounted external to the tank and running my closed loop.

2. A Current Prime Mini In-Line Chiller 1/10 HP.

3. A WP-MD55 external water pump returning water from the sump to the main tank.

 

I am guessing that it is the Mag 12.

 

If the Mag 12 is the culprate, what can I do? Is there a way to fix it? Or should I contact the manufacturer?

 

Bruce

[Coral Hind]

I would unplug the mag 12 and see if you still feel anything.

 

You can open the pump up and check to make sure there are no cracks in the plastic case. I had a rio that cracked inside where the propeller sits once. Depending on the age of the pump the company might be able to help you.

 

It is strange that you only feel it in the tank and not the sump. Since they are connected via pipes full of water they should be about the same potential. Are you touching anything else while you stick your hand in the tank?

[bbyatv]

Thats what I thought. No. I am not touching anything else. It is very different between the two. I have a small cut on my finger and it is a good sting on that cut in the main tank and I do not feel anything in the sump.

 

I am going to unplug one thing at a time and see if I can narrow it down.

 

Bruce

 

It is strange that you only feel it in the tank and not the sump. Since they are connected via pipes full of water they should be about the same potential. Are you touching anything else while you stick your hand in the tank?

[BeltwayBandit]

Here is an interesting article on ground probes.

 

I may not want one.

 

http://angel-strike.com/aquarium/GroundingProbes.html

 

Bruce

 

 

I HATE that article. I have debunked it at least twice on these forums. The information provided in that article IMO is pure bunk. A grounding probe with a gfci is a best practices solution for reef safety from an electrical standpoint.

 

Here is a cut and paste of one of my debunkings of that horrible piece of advice:

 

Ahh yes one of the classic 'arguments' among reefkeepers...

 

To ground or not to ground. That is the question.

Weather it is safer for the fish or the keeper to suffer

The ping and tingle of stray voltage

Or to put safety first

And by grounding, end them. To ground, with current...

No more... and with GFCI we prevent

The heartache, and the thousand natural shocks

That stray current leads to.

 

ok... enough butchering of Shakespeare.

 

There are two separate and distinct issues with grounding probes. Unfortunately these issues often get lumped together and thus the confusion is born.

 

There are two different sources of electric potential in your tank. Yes two. The first, is stray current from an improperly grounded or short circuited piece of equipment. If your equipment has a 3 prong plug, then it is likely that a short in the equipment will cause your GFCI to trip without a grounding probe. If you have any two prong (i.e. ungrounded) items, it is unlikely that your GFCI will trip without grounding the tank. I have been shocked by a tank, protected by GFCI, but ungrounded. It is entirely possible. In this scenario, grounding a tank should be a no brainer. If/when a piece of equipment shorts out there will be a momentary current from the equipment to the grounding probe. This will introduce an imbalance on the hot and neutral legs that your GFCI will detect and it will trip offline. We are talking less than a second here that current will flow through some portion of your tank. IMO that brief instant is not worth the risk of running a system ungrounded.

 

The second source of electric potential is not so clear cut. (and IMO the source of most of the confusion surrounding the issue). This involves induced voltages. I'm not going to go into the theory, but suffice it to say salt water is a good conductor of electricity and having electrical equipment in and around it can create an induced voltage. It is this stray voltage, that when left alone merely raises the electric potential of the tank, yet when a ground probe is introduced it will cause some minute (see link below to see how minute) amount of current to 'flow' through the tank. This is the current that the anti-ground probe folks are using to justify their opposition. I found the following paper on reefs.org that should throw cold water on this particular urban legend. As you will see, the induced current is so tiny (on the order of 10^-9) it truly can be considered trivial.

 

So, there you have it. That is my take on the issue.

 

BB

 

http://www.reefs.org/library/aquarium_net/1298/1298_3.html

 

PS: please, no one post that horrible website from Georgia Tech on this subject. That paper has to be one of the worst articles I have ever read on this particular subject.

[Gatortailale]

I HATE that article. I have debunked it at least twice on these forums. The information provided in that article IMO is pure bunk. A grounding probe with a gfci is a best practices solution for reef safety from an electrical standpoint.

 

 

BB

 

http://www.reefs.org/library/aquarium_net/1298/1298_3.html

 

PS: please, no one post that horrible website from Georgia Tech on this subject. That paper has to be one of the worst articles I have ever read on this particular subject.

 

 

I agree with BB. I've run a ground probe on all of my tanks for years and have never had a problem with them.

[amos]

Great information. Now why is it that one could feel voltage as a "sting" from a cut?

[bbyatv]

Good question. I do not feel anything on my other fingers that do not have cuts.

 

Bruce

 

Great information. Now why is it that one could feel voltage as a "sting" from a cut?

[flowerseller]

Problem solved,

 

Bruce, use the hand without the cut until it heals up, then resume normal operations

 

 

 

I've used a GP for the last 18 years and think the article in question is just that.

 

 

 

Get a good quality grounding probe and remember, not all stainless steel is stainless steel.

[bbyatv]

Chip,

 

You are the master of the obvious.

 

I plan on adding a probe to both the tank and refugium. I also plan on trying to eliminate the voltage leak that is causing the problem in the first place.

 

When it comes to Stainless steel, go with Titanium. If you must use stainless make sure it is 316 marine grade. Or just find a substitute for steel all together.

 

Bruce

 

Problem solved,

 

Bruce, use the hand without the cut until it heals up, then resume normal operations

 

 

 

I've used a GP for the last 18 years and think the article in question is just that.

 

 

 

Get a good quality grounding probe and remember, not all stainless steel is stainless steel.

Edited September 12, 2008 by bbyatv

[Jon Lazar]

Great information. Now why is it that one could feel voltage as a "sting" from a cut?

 

I would speculate that the skin "inside" your cut has a lower electrical resistance than the rest of the skin on your hands.

 

Jon

[Sharkb8]

Great information. Now why is it that one could feel voltage as a "sting" from a cut?

 

Cool biology question. I have no answer. But, as usual, I have two ideas on the subject:

 

a) the combination of salt water and voltage together hitting a break in the skin may be synergistic, i.e. causing a much more heightened sensation of shock. Salt water stings any open wound. But the combination of that sting plus the voltage may somehow amplify the sensation.

 

b) skin is not as good of a conductor of electricity as is blood, or more accurately, salty solutions with ions in them, like blood, body fluids, etc. So, electricity is just picking the quickest route to the ground, through the cut, rather than through several layers of skin.

 

Could be a combination of the two. Could be some other totally unrelated reason too ...

 

P.S. If you want more detail, we can discuss pain receptors on the surface of cells, voltage-gated ion channels in cells, endorphins, neuronal synapses, etc etc

Edited September 12, 2008 by Sharkb8

[amos]

So let me add some more weird observations. I actually had the same thing happen to me the other day. I felt a "sting" from a cut on one of my fingers. I verified that when I turned off all of the devices, it stopped (I also plugged in one by one and every one of them caused the sting to occur on their own). Then I realized I also had a cut on another finger. When I stuck the second one in the water, the sting went dead. It only stung when I had one of the two fingers with cuts on it.

 

Am I just imagining things?

 

Jon