If the other tank is ok, I do not think it is this plug in stuff, though I never use them as both tanks would have been affected. I suspect it is a chemical, from the superglue, acetone or chemipure or from the tank itself, that poisoned your tank. I usually use a big chunk of water from my old tank when I set up a new tank, to keep the water very similar and reduce the acclimation shock. I have lids on my tank, I doubt that it causes a depletion of O2. You seem to have done things the right way so I lean toward a chimical in your new tank.