How To Test for Stray Voltage
Purchase or borrow a voltage meter. They can generally be found for less than $20 at most automotive parts or hardware store. Try Canadian Tire:
Mastercraft Deluxe Digital Volt Meter for Sale $14.99 Reg. $54.99
Turn the selector to "120 AC Voltage".
Insert the tip of the black probe into the third or "grounding" hole in an electrical outlet.
Insert the metal tip of the red probe into the tank water.
Watch the meter for any changes. Any changes 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.
[sub]Source:
http://saltaquarium.about.com/od/aquariummaintenancecare/a/aastrayvoltage.htm[/sub]
And yes... stray voltage can cause your fish to go lethargic. Also
Head & Lateral Line Erosion Disease (HLLD)
