Earlier, I mentioned the thing about the stainless steel aquarium hood. Thanks to a couple of those things, I had electric aquariums way back in the 1950s. At the time, the nation was still getting over one war and preparing to fight another, so the aquarium hobby was sorely lacking in both enthusiasts and a technology base. What I'm trying to say is that our engineers were not really thinking much about aquariums at the time.
To get even with them, I wasn't thinking much about the principles of magnetism and electricity at the time. For that matter, neither was the guy who designed the stainless steel aquarium hood. It did look pretty nice atop the stainless steel frame of the aquarium, and regular light bulbs illuminated the murk in the tanks.
Actually, it doesn't bother much if the entire aquarium is at a 115 volt electrical potential, which mine was on account of the mist that the bubbling filter put on the inside of the hood. The problem comes when a person whose body has a different electrical potential touches the aquarium. Since I wasn't grounded, it was only a little zapp at first.
Starting a syphon, though, was an act of courage -- well, actually stupidity -- because of two potentials: electrical shock and cootie ingestion. In addition, the mystery snails were unable to lay their eggs on the inside of the hood. Some of them didn't survive the attempt.
Electrical plugs did not have the large and small prongs, so it was easy to have the hot and return sides reversed for any two aquariums. I first got worried about the problem when I had my hands in two aquariums at once. Then the spark of an idea hit me. Maybe the fish and plants are also somewhat uncomfortable with the polarity situation.
It wasn't too much later that I bought my first frameless aquarium sealed with clear silicone and topped with a glass hood and a plastic light fixture. Ain't technology wonderful.
Thats so crazy! I bet copper would be pretty too! Too bad i always break my glass tops! And that thick nice acrylic is sooooo expensive! Reminds me I need to get tops for some tanks. It is getting humid in my wooden living room! 
