For the first time since 2017 I took my plumbing from my overflow boxes, and boy was is crazy what and how much gunk was at bottom on overflow boxes. It was like 2" of mud there. Maid me think of ways to prevent. one way is clean them more often like I just did. I copied picture from brs website for display only. But what would happened if this portion of pipe shown in picture would be extended all the way down to the bottom of the tank? So It can siphon waste that falls into overflow. I got total of 4 of these drains 2 per box.