Hi,
This little story is about a freshwater tank. Years ago I had two 30g long tanks on a metal stand one beneath the other. One day I came home from work, the top tank was half empty and the bottom tank was overfull, to the very rim, if a fish moved too fast it splashed water over.
I originally thought I had a leak and the top tank had drained into the bottom tank…However when I filled the top tank, no leak at all. I checked the pumps, maybe it was to blame, no all was fine and working properly. Nothing, no reason for a leak at all. The fish in the bottom tank would die, the ones on top got ich.
Three months go by, and I came home and it happened again, the top tank was exactly ½ full and the bottom tank totally over filled. Again I checked everything, nothing was leaking.
This went on for a year, out of the blue for no reason sometimes weeks and sometimes months apart, the top tank would be down and the bottom over full. The fish would get sick with ich, and I was constantly losing the bottom fish whenever it happened, they just died.
The mystery was finally solved when I went to move. My landlord, an old lady came bounding down the steps, she lived upstairs. She nearly fell she was rushing so fast…”Don’t toss out the fish water, they are so good for my berries!” Turns out this little old lady was sneaking into my apartment when I was at work and stealing my fish tank water. She was too frail to refill the top tank but she filled the bottom one just fine with tap water not treated for chlorine, hence why the fish in the bottom tank were dying.
