This always sucks. I pulled a really stupid one last year. Was doing a water change, added dechlor, and started filling the tank with tap water. This can take quite a while, so I usually do something else, and check back on the tank level from time to time. Well, I forgot. Woke up the NEXT MORNING to a flooded basement, and a tank full of dead fish. There was only enough dechlor for the gallonage of the tank, so chlorine poisoned about 20 breeding tilapia. Luckily my basement is unfinished, and I had replacement tilapia in the pond. I beat myself up about it for a few days. You are not alone Cecil.
I always set an alarm now.
It's all relative as my situation pales compared to what is going on right now in Japan. And if I get a system going where the potential is to lose a lot of money I won't be leaving anything to chance then, so in the long run it has silver lining to it.
