Although highly unprofessional, it's cases like this where I think about all the livestock that dies daily in shipping and in the hands of amateur (and experienced) and "experimental" aquarists.

+1, though a zoo should know better.

This is way different then that. A zoo charges for addmission and is expected to know at least something of the species they keep

when this first happened i guessed oxygen levels, i really wish we could see the entire set up,kinda wonder what kind of goodies they have hooked up

My guess is a mag 3 pump with a rena air pump and one of those circular air stones.

Does that make sense?
 

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?

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%.

touchee

you would think that the keepers would be passionate enough to do copious amounts of reading on the species they keep and just marine life in general the problem is most people today have a lack of passion for anything but miller time, so just keep flaming the zoo:onfire: they deserve it for a boo boo that big but even more importantly did they never check their PH Im sure that would be the first indicator that something is amiss:sad:

I was at the zoo a few days before the rays started to die and you could notice something wasnt right. red algea was all over the tank and water wasnt that pretty either.