Following various guides online I installed the plastic screen on my waterfall scrubber right inside the slot that I had cut into the PVC pipe. The issue with this (for me) has always been that this has caused occasional streams of water to squirt out from the slot in random directions...sometimes out of my sump and onto the floor So today I moved the screen outside of the slot and left a 2mm gap between the exit of the slot and the plastic screen. The water flowing down my screen has never been so even! It covers the entire screen in quick flowing water and there is absolutely no spraying in random directions. Furthermore I'd be willing to bet that algae doesn't find its way into the slot and small particles of gunk wont build up in there either. So why doesn't everyone do it this way?