So last night I looked at my tank and I was fooling around with something and I noticed my Ozonizer didn't have the light on and according to the read out, it wasn't making any Ozone. So I remove the thing and I have a spare one. I don't remember where I got it but I put it in and turn it on. It's a Gen-X Ozonizer but there isn't any read out on it and no way to tell how much Ozone it is making so I set it at the lowest setting. My old one put out 200mg ozone but I didn't know what this one puts out. I have been running Ozone full blast for decades so I didn't think anything of it and left it on.
This morning I come down to feed the fish (the tank is in my finished basement) and I notice my copperband butterfly is up at the surface sucking air. (Either that, or he was looking at the picture of the Supermodel I have hanging on the wall and he is trying to whistle)
I shot some live blackworms in the tank and he usually chases them down all over the place. He stays up on top sticking his nose out of the water. This is not good as he has never done that.
Then as I am watching him, I see something red laying behind a bottle, obviously dead. My fish are well aware that they are not allowed to die unless it is from old age so now I am concerned. I carefully look around at the other fish and they looked a little "off". OMG, what happened?
I go around the back of the tank and check the temperature. It is a little low, but it's not like I am going to see a dog sled team flying past the tank carrying an Eskimo so I dismiss that as the cause and just bump up the temperature a couple of degrees. The skimmer is also putting out a lot of foam.
I look for a hospital tank, which I have not used since probably Jimmy Carter was President and I start to mix up some water.
I don't know why because I don't even have any medications and I don't know yet what is wrong with the fish. I remove the dead, red fish which was an old cardinal who I was kind of fond of. I have no idea when I got him. It could have been five, ten or fifteen years ago (I have a lousy memory),
I autopsy him mainly looking for parasites. His gills are clean, not one parasite.
I look at the copperband, who is a really good friend of mine and he is staring at me like, What is wrong with me? Call a doctor. He is also breathing much faster than normal.
Then it hits me. I smell Ozone. I don't normally smell anything because my smeller works as good as my memory. Just then my wife yells down for me to bring something up, or she was telling me how good looking I am, I forget, but either way, I yell back to her, "MY FISH ARE SICK".
She tells me that in the middle of the night she came downstairs and the entire basement smelled funny with a strong odor.
She was right, that little ozonizer filled my entire basement and tank with tons of free Ozone.
So I Google that Gen-X ozonizer and there are all sorts of bad things written about it. First of all the rheostat that adjusts the amount of Ozone isn't even connected to anything so it puts out at least 250mg of ozone all the time even though I thought I had it on the lowest setting. I am sure it puts out way more Ozone than that to fill my entire basement after going through my 5' skimmer.
So I immediately shut the thing off. We went out to my Daughter's in Manhattan for most of the day and now the fish look normal, except for the copperband. He looks better than he did before but is still breathing faster than normal as Ozone would deteriorate the delicate gill filaments.
I am not sure if he is going to make it, it depends on how fast his gills heal. I really like that fish so I hope he lives as he is my favorite and is the first one to greet me when I come home. He is also my biggest eater. If he dies, I will replace him but I really hate to lose a fish, especially to a stupid error or a mechanical breakdown.
Oh no!! 
