I only have a 3 chamber sump, my middle (skimmer) section had some free room so I used some black egg crate to split that chamber in two. I used the extra (new) chamber for chaeto however when my system goes into feed mode the water level rises and some of the chaeto will make its way into the bubble trap. I built these extensions to sit ontop of the glass baffles to keep the chaeto in place. I have an aquarium masters glass sump, it appears to be a modified 29 gallon aquarium. I printed two of these for each baffle. The jpeg is two of these snapped together, they fit perfectly after I snapped of the extra tabs on the far end.
