Plumbing return question

[GeoHawk]

I am plumbing my return from my frag tank to my sump and it is connecting to my drain from my display. I am using barb and hose. My question is can the hose drop a little below the connection to my drain from the display without backing water back up into my frag tank. It will likely drop abot 2-3 inches below and be forced back up to a lower point than where it exits the frag tank. Any help would be great this is my first time doing this.

 

[AZDesertRat]

Photos or a sketch would really help visualize your concept. My first reaction is if you are plumbing in to the displays overflow or drain you may have a potential flooding issue but without a sketch showing elevations it is hard to answer. Is the frag tank above or below or the same level?