Here we go again: MIs, Take III

[Aquattro]

Honestly, even with O2 as a strong suspect, unless we monitor full time and chart values and find a sudden dip coinciding with a fish death, it's still mysterious dying fish syndrome.
The 2 in town that died. Tank is stable, nothing of any significance changes day to day, no power outages, etc. Fish survive fine for 6 nights, both die on 7th. What happened that could drop O2 to lethal levels on that night and not the others? Maybe something. Maybe not.

I did lose a MI and 2 large angels in a confirmed low flow setup overnight. I now have 2 MI doing well in a tank with surf conditions. But unless I spend a grand on an Apex DO meter and log O2 variances, we can't be sure what it or isn't happening.