Well, after reading all I could find about scrubbers, I have a prelim design for what I want. This is for a new 125.
My main concern is... ease of removing the screen for cleaning, since this will be a weekly chore. Here is what I came up with. The screen tube sits in the lower tees and just lifts out. The top tube provides the water. Depending on the flow from the top tube, I may install a screen in it to direct flow to the screen tube. Obviously there is still flow testing to be done, etc. to get it right.
I am going to have a submersible pump with an overflow feed. Opinions welcome...