Perfect timing.......
I just finished a new bio reactor (moving bed filter) that addresses several issues I've found with previous reactors over the years. I'm pretty proud of this thing, as I've found flaws with EVERY single one I've ever built. BUT unfortunately these flaws aren't something you can notice in the first year or 2 of running, but after several years there becomes failures that must be either maintained or they become an unavoidable failure.
K1 is the eel of media. IF there's a way to get out it WILL find it.