How To Test for Stray Voltage
1. Obtain a voltage meter. They can generally be found for less than $20 at most automotive parts or hardware stores.
2. Turn the selector to the lowest “AC Voltage” setting range from 0-200.
3. Insert the tip of the black lead to a ground source and drop the red lead into the aquarium.
4. Watch the meter for any reading. Any reading may indicate there is voltage leaking in your system.
How To Identify the Voltage Leak Source
Disconnect each electrical appliance (heaters, pumps, lights, chiller) associated with your tank one at a time and retest for voltage after each unit is disconnected. To be certain the suspected product is leaking current, remove the item and place in a bucket of water outside of the confines of your aquarium, plug in and retest.
How To Solve the Voltage Leak
Replace (recommended) or repair the faulty unit. Always 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.