The shulker search engine Etho created in one of his videos: www.youtube.com/watch?v=pEbS5-OgEbM&t=706s

I've made it slightly more compact (not necessarily faster though). This map includes structures ("minecraft:j1, minecraft:j2, ..., minecraft:j9) for making my compacted version step by step. The structure "minecraft:j9" is the completed build.

Loading the structure may have issues with water spilling into blocks where it should not, or with the filter item (reeds) being ejected. Simply remove any excess water and refill the filter to fix this. Please watch my YouTube video for the full explanation, as well as the step by step build tutorial.