Short circuit and coral disaster

[Charles Silva]

Hello

Im new here and I would like to share a short circuit event at a friend's tank that resulted in all SPS corals death.
We are trying to understand the poisoning cause and here is the brief story.
He had to remove the refugium light fixture (to do a maintenance in this tank) and his plan was install it back next day.
Someone accidentaly dropped the socket with the wires inside the sump and as programmed on Apex Controller this outlet turned on at 22 o'clock.
Around 23:30 he arrived at home and the room was smelling egg and many corals were dead and fish suffering.
He removed the wires from the sump and checked the Apex log graphs that demonstrated an electrical current peak at 22:00 (short circuit) and a suddenly decrease in ORP.
As a remediation plan he did a 50% water change (but in the morning he lost all SPS).
The copper is reading 0.1 pmm.
Looking the attached snapshot we can see the graphs and the photos are showing that the inner socket connection "melted" and the alluminium bar where it was fixed corroded too.

Could someone with water chemistry experience explain me with some equations what happened as it leached poison metals ? Could be the copper wire ?

The system has 200 gal total and Im impressed how fast this toxic intoxication took place.
Assuming other situation without a chemical reaction could only this electricity (110 v) be harmful in a non water grounded system ?

Regards,
Charles - Rio de Janeiro

Photos:

 

[mcarroll]

hydrolysis causing an O2 (or H2?) overload?

Hard to compare with just 120v wires going in a tank since from a fluorescent ballast there could be some crazy voltages going into the tank.

 

[bif24701]

I'm no chemist, but I assume that the electrical current sped up the corrosion by increasing its difference in charge and thus easier to bond with oxygen in the water to form the oxide of the metal.

 

[Randy Holmes-Farley Verified Community Expert]

If a copper wire is in the tank and current is flowing, copper can be released from the surface into the water:

Cu(metal) --> Cu++ + 2e-

Copper wires can also corrode with no current flowing, but more slowly as the surface is oxidized.

 

[Randy Holmes-Farley Verified Community Expert]

The ORP reading during current flow may not be accurate.

 

[bif24701]

If a copper wire is in the tank and current is flowing, copper can be released from the surface into the water:

Cu(metal) --> Cu++ + 2e-

Copper wires can also corrode with no current flowing, but more slowly as the surface is oxidized.

The real question though, was I right!? Lol