I have this in my 45 which doesn’t have a ton of excess nutrition yet thanks to sponges catching most of it. It’s in the middle compartment of my AIO as seen in photo but even on the lowest setting fills up instantly with water.
this is rated for a 20 gallon but is too strong for a 45??
I have a Z-Series Bubble Magnus skimmer and in my experience, these protein skimmers take FOREVER to break in. You may just have to wait it out. You can pull the plug and allow the skim to go right back into the tank so it doesn't keep overflowing.