The Durso Standpipe is designed for use in an internal overflow chamber which surface skims the water. The Durso Standpipe helps to quietly drain water to the sump below. Aquariums made with an internal overflow are commonly called "Reef-Ready". Aquariums lacking this feature can be adapted to use a sump by adding a "hang on the back" (HOB) overflow which use a mechanism of some type to create a siphon to lift water over the rim of the aquarium and into the hang-on box which then drains down to the sump.
The Durso Standpipe is not designed to fit into these small hang-on the back overflow boxes. However, I have received feedback that people have cut the standpipe to a very short height and adapting it to the limited space in the hang on box. This is currently not recommended or supported by us.
Florin Ilia provided a video of one of our Durso Standpipes with strainer in a CPR C590 hang on the back overflow:
NOTE: He stated "the sound in the clip is misleading, it is coming from the open cabinet, not from the overflow".