AF, the suggested start up is 15 minutes the first day, 30 minutes the second day, 1 hour the third day, and continue to double the run time each cosecutive day.
10 or 15 minute runs every 2-3 hours is pushing a lot of the anoxic water in to your good water and not allowing the time for the bad gasses to be safely releaased. The noxious smells you "tasted" is as deadly to the fish as it is offensive to our senses.
What compounds the dangers for a fish kill is that this is absolutely the worst time of year for starting an aeration system. Hopefully your venturi system created enough circulation that only your deepest water is toxic.
