Sorry for your loss. I've done the same thing so many times...I don't think I've remembered once to turn it off. "Honey, are you watering the backyard? Oh *&#".
I may have a solution now...I heard a talk from a professional Koi grower the other day who said he just leaves a hose running into the waterfalls, or any place the water mixes well before getting to fish. He left the water running 24 hours a day on a slow trickle. I think that would work for me, just accept the fact that I'm going to forget, so just leave it trickle. Might take a couple of days to top off but no harm.
In water features I've used a horse tough float filler supplied with water from an automatic sprinkler valve as a fail safe. Set the valve to just open for minute or two a day was enough for the water feature.