Hi there, and welcome to the Flow forum!
I have a few suggestions, some will answer what you asked, the others will address things that you can prevent. 
- Try flexing your plastic Flow frames gently. If they don’t give much, the wires are tight enough. If they flex a lot, or even fall apart (heaven forbid!), you need to tighten the wires. Cedar has made a video of how to do that:
Sagging Flow frames - #5 by skeggley - Consider waxing the Flow frames by painting on melted wax or just rubbing some burr comb from a hive inspection onto the plastic frame faces. That makes them smell like the hive, and the bees will go up and investigate much sooner than if you don’t.
- Make sure you use a queen excluder below the Flow super. If not, you will get brood in your honey - yuck.
- Read @busso’s post above.