Power outages and don't know if my air pump is enough for oxygen

Hi Guys

Me again, i was wondering if one of you could perhaps help me with this.

We seem to be experiencing alot of power outages lately where i live and I am always stressed that my airpump is not enough to supply oxygen to the tank.

I have a 250L community tank and I have added a Hailea URS 1200 AC/DC airpump lately that has a battery back up.
http://www.hailea.com/E-hailea/product1/uas-12000.htm

Everytime the power goes off I add a couple of oxygen tablets and don't feed the fish but still get up every hour at night to take a bucket and scoop some water up and drop it back in from a height to create some surface irritation to add oxygen.

When the power is on my tank runs perfectly as my water pump creates a lot of surface movement.

The airpump is rated at 5L/min, but still not sure if it is enough.

Any feedback would be appreciated please.

 

Hi we had a power outage for 13 hours last week and i did not loose any fish in my 25 tanks.I just did not feed them and my temp in the tanks only dropped with 1 degree.My tanks are in a fish room and i think that helped with the temp.I do not have battery backup and the fish were ok.I must admit it was a long stressful 13 hours.I am planning to get some battery pumps as well just for future backup.