Papercuts and Stray Voltage in the marine aquarium

Posted on August 5th, 2011 by 11

A few days ago, I gave myself a small papercut on one of my fingers. I don’t think there are many positive attributes with a paper cut. But yesterday, that same paper cut clued me into some stray voltage in my reef aquarium. I was doing a water change on my tank, and felt an immediate stinging at the site of the papercut. Now, we all know salt water will sting a cut. But it usually goes away quickly. I remembered the last time this occurred, it was due to a small amount of stray voltage. It was not something I could feel with the hand that didn’t have a cut on it.

I promptly pulled out the multimeter to verify my findings and isolate the source. It turned out to be a powerhead that feeds the calcium reactor. Unplugging the powerhead brought the voltage down on the multimeter, and the stinging sensation in my finger was gone. I guess it’s time for a new powerhead.

I don’t advocate using your hand to test for stray voltage! But if you feel a sting or tingle in a papercut or hangnail while servicing the tank, it would be wise to test your tank with a multimeter. To test for stray voltage, insert the black probe into the ground port on an outlet or extension cord and the red probe in your tank. If the meter registers voltage, then you should proceed to disconnect each electrical device until the voltage drops. If you disconnect each device one-by-one, the culprit is easily found. Multimeters are pretty cheap and can be found at any home improvement store.

I also recommend getting a grounding probe, and investing in GFCI outlets. While the stray voltage I found was not life threatening, there are cases when a GFCI could save your life.

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  • Anonymous

    There are numerous threads on the internet that explain why using a multimeter to test stray voltage is unreliable and most of the time completely wrong. There are also extreme drawbacks to using ground probes in a tank.

    There is no definitive right or wrong way, but please do more research or give the flip side of the coin before giving out advice.

  • http://pulse.yahoo.com/_726AKG3WUK7TTOKUBI7XRK3ECE Mark

    It is true that a multimeter will pick up induced voltage from magnetic pumps and fluorescent lights, and give a deceiving result. However, it is still a great way to isolate stray voltage, because it can help identify other culprits. 

    While a ground probe can hide potential issues, it can also save your life. I don’t see that as a drawback.

  • http://www.facebook.com/profile.php?id=100001443324671 Patrick Jewell

    erg

  • http://www.facebook.com/profile.php?id=100001443324671 Patrick Jewell

    Why is a ground probe a bad thing? Draw backs?

  • Michael Ornellas

    Yeah the mutimeter is a much less painful way of testing for stray voltage than a hangnail… If posters want to disagree with my statement then they should also include an alternative suggestion.  And ALL electrical components around water should be grounded and use a GFI plug.  Seriously guys, I’m a firefighter… Just because a fire happens in your house dosn’t mean you will be the only person affected by it.  Fires can spread quickly from occupancy to occupancy and in the extreme heat and drought many of us are in right now people’s risk of injury to a fire goes up dramatically.  Be smart with your hobby, don’t be careless with electricity.  :) ’

  • Michael Ornellas

    Yeah the mutimeter is a much less painful way of testing for stray voltage than a hangnail… If posters want to disagree with my statement then they should also include an alternative suggestion.  And ALL electrical components around water should be grounded and use a GFI plug.  Seriously guys, I’m a firefighter… Just because a fire happens in your house dosn’t mean you will be the only person affected by it.  Fires can spread quickly from occupancy to occupancy and in the extreme heat and drought many of us are in right now people’s risk of injury to a fire goes up dramatically.  Be smart with your hobby, don’t be careless with electricity.  :) ’

  • http://pulse.yahoo.com/_3LLNDZ5XJ6ZQ76J2VLDUQD5WOA Micheal

    Funny the other day I did a watch change, and my little maxijet that I use to mix water up (and the cord is oddly twisted quite a bit due to all the “spinning” it tends to do, well shoes were wet, and I go to plug it in and *bzzzt* yeah… grabbed a pair of wire cutters, cut the cord off it (so no one else uses it) and threw it in the trash.

    I have used hangnails in the past to isolate the problem on tanks too, however the tingle is oh so slight that it safes so much time over getting out a multimeter, just don’t have soaking wet shoes while standing on a concrete slab!   Using something like a DJ power strip can help you as well, since you don’t even need to unplug to test, just flip switches

  • http://pulse.yahoo.com/_TY62P4IMCIOGM5T3WOGV625FII The Jesus

    I agree with you about using a dj power strip.  I use one in my little fish room, where I have my rodi unit, make saltwater for water changes, etc.  Using the dj strip has prevented me from several potentially harmful shocks.  Before using the dj power strip and having good gfci’s put in, I’ve received a few good shocks and a few where I knew I was going to get shocked, but had to just to prevent a fire.

  • Anonymous

    Most building codes now specifically require GFCI for aquariums or will use an umbrella term like “water appliances.” Your homeowners/renters insurance is unlikely to pay if you have a fire or someone gets electrocuted because your work didn’t meet code.

  • Anonymous

    Most building codes now specifically require GFCI for aquariums or will use an umbrella term like “water appliances.” Your homeowners/renters insurance is unlikely to pay if you have a fire or someone gets electrocuted because your work didn’t meet code.

  • http://twitter.com/Anders_Glinvad Anders G. Sørensen

    I don’t know the laws regarding electricity in the states – but here in
    Denmark GFI’s have been law for years.. Can’t believe that’s not the case
    in the states!? Anything else is madness!

    What do you mean by all electrical components around water should be
    grounded? You can’t ground plastic pumps and no one really uses metal
    case pumps. So thats not an option. Allthough you could add a titanium
    probe in the tank which then would trigger the GFI is an stray voltage
    would occur. But then again, you would probably end up with the power
    cutting out all of the time due to constant small and negligible stray
    voltages.