Thanks Tony, I have seen them setup with drastically different water levels. Golds has them almost fully submerged in the store and most online photos show them half submerged. I’ll do the gate valve mod as you suggested.
I picked up a 90 gal in addition to the 67 gal and skimmer so will use one as a sump for the other for my nano frag tank
Since I am converting a tank into a sump I have the ability to set whatever water depth I want.