This is how I have mine
Small separate plastic container fed by separate 600lph pump, chaeto doesn’t tumble, but get good growth. Also have some in sump refugium section, but also doesn’t tumble.
I reckon if you put some egg crate you can partition a section of your return section and have chaeto there. You do need light! Main thing is that you want to prevent the chaeto from clogging your return pump!
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