Thoughts??

[Samw]

Originally Posted by Aquattro

I just pulled a bunch of this macro algae, and I doubt anything ate it. Tough as leather! My next guess is O2 depletion, pumps were at a low setting, plus some cyano and large plants to use it up.

If they all looked fine during the day and were active and eating well and came from established systems (not newly caught), and then just suddenly died overnight (when O2 is at its lowest), and your aeration was lowered during this timespan, then lack of O2 is a good possibility.