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Identifying, Locating and Curing Stray Voltage in a Saltwater Aquarium

How To Identify the Voltage Leak Source

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Whenever electric appliances are used in close proximity to saltwater aquariums, the potential for problems increases dramatically. Fortunately for most saltwater aquarists, a vast majority of equipment used in conjunction with an aquarium is of high quality and seldom fails. However, when an appliance does fail and leaks electricity into a tank, it is called "stray voltage".

Stray voltage, even in small amounts, can cause a number of subtle or dramatic problems in an aquarium.

  • HLLD (Head and Lateral Line Erosion Disease) Anecdotal evidence in aquariums as well as observations of fish in close proximity to hydroelectric dams have indicated that stray voltage could be a possible cause of HLLD in fish.
  • Sudden Death of Tank Inhabitants Many aquarists have tested for voltage leaks in their tanks after experiencing a sudden and otherwise inexplicable loss of fish in their tanks and found that a faulty appliance used in conjunction with their tank was the cause.
  • Unusual Behavior of Tank Inhabitants - When continuos strange behavior such as a rapid and jerky swimming pattern or frequent quivering of tank inhabitants is observed, many aquarists have discovered that the cause was stray voltage.
How To Test for Stray Voltage
  1. Purchase or borrow a voltage meter. They can generally be found for less than $20 at most automotive parts or hardware store.
  2. Turn the selector to "120 AC Voltage".
  3. Insert the tip of the black probe into the third or "grounding" hole in an electrical outlet.
  4. Insert the metal tip of the red probe into the tank water.
  5. Watch the meter needle for any movement. Any needle movement indicates a voltage leak in your system.
How To Identify the Voltage Leak Source
  • One at a time, disconnect each electrical appliance (heaters, pumps, lights, chiller) associated with your tank, retesting for voltage as described above after each unit is disconnected. Heaters and pumps (powerheads) are the most frequent cause of voltage leaks.
How To Solve the Voltage Leak
  • Replace (recommended) or repair the faulty unit. Test the tank once again to make sure that you have eliminated the problem.
  • Install a simple grounding probe in the tank to avoid damage to the tank inhabitants. This may temporarily take care of the symptoms of stray voltage, but it does not cure the cause of the problem.
Many aquarists test their tanks for stray voltage on a regular basis as a part of their normal tank maintenance routine. Detecting a voltage leak problem in its early stages can help eliminate or reduce problems in the future.

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