Stray current

[Reignfire]

I’m at a loss. I’m testing for stray voltage in my aquarium and using multiple multimeters. Over the last 2 weeks everything started to die. First all the inverts, then the corals, then the fish. I tried everything I could think of. I switch salts ( thinking it was bad salt?) and did multiple 75% water changes, added carbon, tested and tested my water over and over. So I decided to test stray voltage. My results left me with way more questions. I inserted the black (-) probe into the ground of an outlet and the positive probe in the water. Im getting 2.89VAC with everything turned off...(Literally everything unplugged and taken out of the water. How is that possible???) 16VAC with the heater. 10VAC with canister filter. And 41 VAC with Nero3... However with everything plugged in I'm still getting around 41-42VAC.. Again how is this possible.

 

[griss]

@Paul B @wvned any thoughts?

 

[wvned]

Voltage is all around us in the environment. If one of the AC devices like the heater had faulted to the water you would read line voltage, ~110 in the US. Modern DC motors that use pulse wave modulation to control the speed of the motor can read almost anything on cheap meters hobbyists have.

Your title says current.

Have you measured your current to ground? I doubt you have much since you haven't mentioned getting shocked though.

Most likely what you are measuring is induced current which is mostly harmless.

AI blab blab
Induced current in a fish tank arises primarily from electromagnetic fields generated by electrical equipment such as pumps, powerheads, and fluorescent lights, which can induce a voltage potential in the water due to their proximity to the tank. This induced voltage is a common occurrence in aquariums with electrical devices, and it is typically not harmful to fish or aquarists because the current flow is minimal and lacks a complete circuit to ground.

That last part. Lacks a complete circuit to ground.
Add a ground probe to your tank. All the induced voltages will disappear. It will also provide a way for a GFI to work before you stick you hand in the tank if there is a fault.
Actually they wont disappear, they will still be there but you cant measure them anymore.

Now the nasty part. If a wire gets exposed to water in the tank it is most likely made from copper. It is the copper driven into the tank water by electrolysis that kills everything usually and not the electricity.
With stuff unplugged feel and look thoroughly at all the cords that enter or are around the tank and make sure none of the insulation is damaged. A tiny film of dampness with salt can bring power to the tank from a cord that doesn't actually go in it. The salt from splashes evaporating will draw enough moisture from the air to make this happen.

My cat as a kitten loved to chew on wires in places you could not really see them. This was a real problem a few times.

Also check anything with magnets. They can be a real poison bomb if the coating breaks down and exposes the magnet to saltwater.

 

[Reignfire]

Voltage is all around us in the environment. If one of the AC devices like the heater had faulted to the water you would read line voltage, ~110 in the US. Modern DC motors that use pulse wave modulation to control the speed of the motor can read almost anything on cheap meters hobbyists have.

Your title says current.

Have you measured your current to ground? I doubt you have much since you haven't mentioned getting shocked though.

Most likely what you are measuring is induced current which is mostly harmless.

AI blab blab
Induced current in a fish tank arises primarily from electromagnetic fields generated by electrical equipment such as pumps, powerheads, and fluorescent lights, which can induce a voltage potential in the water due to their proximity to the tank. This induced voltage is a common occurrence in aquariums with electrical devices, and it is typically not harmful to fish or aquarists because the current flow is minimal and lacks a complete circuit to ground.

That last part. Lacks a complete circuit to ground.
Add a ground probe to your tank. All the induced voltages will disappear. It will also provide a way for a GFI to work before you stick you hand in the tank if there is a fault.
Actually they wont disappear, they will still be there but you cant measure them anymore.

Now the nasty part. If a wire gets exposed to water in the tank it is most likely made from copper. It is the copper driven into the tank water by electrolysis that kills everything usually and not the electricity.
With stuff unplugged feel and look thoroughly at all the cords that enter or are around the tank and make sure none of the insulation is damaged. A tiny film of dampness with salt can bring power to the tank from a cord that doesn't actually go in it. The salt from splashes evaporating will draw enough moisture from the air to make this happen.

My cat as a kitten loved to chew on wires in places you could not really see them. This was a real problem a few times.

Also check anything with magnets. They can be a real poison bomb if the coating breaks down and exposes the magnet to saltwater.

Thank you for that detailed response. I’ve checked for all possible damaged wires and checked all magnets. I ordered an ICP test. I’ll post the results if anyone is curious.

 

[wvned]

Might help​

Poly Filter Aquarium Filter

Poly-Filter turns color when removing medications.

• Aqua to Dark Blue: Copper or Copper salts.
• Orange: Iron.
• Bright Red: Aluminum.
• Bright Yellow: Ammonia, Amines or Solvents.

Poly Filter Aquarium Filter At Bulk Reef Supply