How long should I run feed mode?

[AV8R]

I am setting up an apex on my tank and the normal feed time is 10 mins. I don't think this is enough time for my filter feeders to consume the marine snow out of the water. How long should this feed time be? I was thinking about setting it for an hour. However my return pump would shut off during this time and the display would be without a heater for the duration of the feed. Is this too long to go without a heater? The display is 54 gallons. Any opinions?

 

[Hemmdog]

0-15 mins should be fine. My return pump doesn’t go off for any reason other than water changes or a power outage.