Calgary zoo rays die due to human error

[Samw]

I guess it depends on their bioload. In my tank, oxygen levels can drop really fast overnight. Recently, I've neglected to clean my pump intakes causing the skimmer to stop aerating my tank and I lost the highest oxygen demanding livestock overnight when CO2 was highest and there was no photosynthesis taking place. When I measured the oxygen that morning, it had gone down to below 50% even though I had 2 powerheads and an overhead sump overflow return moving the water. When I have my lights on during the day, the levels are over 100%.

Originally Posted by jslaney

Not to question the big wigs, but that is a relatively shallow tank with a huge amount of surface area. Even if there was no water movement does low O2 make sense?

Unless bacteria started using all the O2 (which would be noticed by green water) this does not seem possible.

You could probably shut off all the pumps and still have enough O2.

What do you guys think?