My Tank crash - Hopefully you can learn from my experience :(

[ComfortablyNumb]

Heat could have killed the fish too. Poisoning is also a possibility. Over-dosing meds or additives also. To say 02 deprivation is the only possible source is short-sighted in my view.

I know some tanks are different than others, but the same laws of physics and chemistry apply to all. I have never heard of any reef tank failing due to oxygen deprivation in such a short period of time as the OP surmises. It doesn't make any sense given the vast bulk of evidence indicating otherwise from practical experience by well experienced keepers here and elsewhere.