catfishCain wrote:Firstly I am unsure what killed your two angel fish. I don't think it would have been a shock as the fish would have needed to be grounded. The water and tank do not conduct electricity so to get a shock the fish would have to be touching something like the gravel.
Ehm, how would the gravel be any different than anything else in the tank. Pure water is indeed a very poor conductor. However, pure water isn't usually what you find in a fish-tank, it contains all sorts of dissolved matter, and for electrical purposes dissolved salts of various kinds. The measure of conductivity is what shows how much (or litte) of these salts are dissolved. The levels of conductivity in freshwater is indeed fairly low, particularyly when compared to for instance marine water.
The gravel is almost certainly a good electrical insulator, but even if it wasn't, it's still not in contact with GROUND - there's glass in between the gravel and anything that would be ground - and most fish-tanks stand on some sort of wood-frame, which is also not a good conductor.
However, further down the line of the electrical supply-chain, we do have a ground, that is connected in contact with the water - the electrical supply has two lines : live and neutral. Neutral is essentially ground, just that it's not connected to ground locally, it's connected to ground at the electrical supply-station, same place where the live is connected. Both live and neutral go into the heater, otherwise there wouldn't be a complete circuit through the heater element (one side of the heater element is NEUTRAL, the ohter side LIVE, and the current used throuogh the wire of the element would be what's causing the heat generated).
Finally, I do agree that it's not determined that the electrics killed the fish - it's quite likely we'll never find out.
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Mats