Hey new here but have a snowflake in my 120 with two overflows so hope I can help?
My tank has mega overflows(built in Aqueon) so I used tubing(like for syphon) cut on one side to build the top of my overflows upto glass lid.
I watched my little pencil sized eel swim in and out of the overflow on day one and two,and knew this was going to be a challenge!
I also duct taped the plastic part of lid in back for real!
This was over a year ago and he is a little bigger then a pencil now(around 24" long and over 1" thck).
He should settle in for you hopefully.
Most don't realize that they are the best scavenger going.
If they smell something they will not stop searching(IMO
why they end up in sumps!).
Enjoy him while he is small!
Mine is in a 120 with a lion fish and miniautus grouper and they run when he is looking for the cocktail shrimp I feed(after they stuff themselves!).