You may turn off the powerheads whenever you feed the fish or try to point those powerheads against the glass wall or you may use a timer.
It is wise to have powerheads running 24/7 in any tank conditions. This will avoid dead spots in your tank that most likely turn into a cyano haven. If you're ready to keep some corals,
wave maker w/ timer is the best way to do it. This will mimic the ocean's motion and will keep your inhabitants happy.
But if you don't have a chance to get a wavemaker, poweheads itself should work but make sure not to point all powerheads in one direction. This will cause a swirling effect and it can provide stress to your fish and corals. Have those powerheads face against each other to have more similar ocean flow.
If by any chance you are planning to keep some demanding corals such as SPS / LPS, those 2 powerheads you have isn't going to be enough for a 55G. I have 6 Maxijets 1200 pointed on all directions on my 75G and everything is doing great.
Goodluck!
