How long can fish and coral go without flow?
 

Had a power outage and was just curious. Everything is fine but whats the limit in time?

Depending on the amount of animals/plants eating up the Oxygen in there, a fw hours to a few days. I would get a battery operated powerhead or airstone at minimum to keep the oxygen circulating.

Mine went 8 hr. and lost some of the fish. The coral all came out ok.

They make battery operated powerheads? o.0

Mine went 8 hours early last week and I lost every fish in the system plus a few of the corals.

Dr Fosters has 3 azoo battery pumps for 10 bucks. They use D batteries. I use mine to aerate freshly mixing salt water too.

Vortechs have a battery backup option that lasts for up to 30 hours for 1 pump, 15 hours for 2.