Sump question

[reefmaster70]

SO, I am using an old All Glass Mega Flow acrylic sump for my 75g tank sump to put a refugium in and skimmer, etc. I am putting my skimmer in the center section. My question is, how exactly do I adjust the water level height in the center section. Does that all depend on how much pull the return pump is set to? Or is it simply an issue of filling the sump to the desired level and then keeping it topped off at that level? Photo of my sump attached. I will be getting rid of the Bio ball media and stuff, and just have a big open middle section .

 

[Nate Chalk]

Fill to desired height and set ato!