: Using aggressive glues like standard "blue glue" can react too strongly and potentially melt or deform the pipe walls.
: Water typically moves through a skimmer or settlement tank, into a pump, and then through biological and UV filters before returning to the pond. Koi Pond Construction | Pond Filter Installation - Part 17
While Part 17 focuses on specific plumbing joins, it sits within a larger sequence of constructing a "life support station" for koi, which often includes: : Using aggressive glues like standard "blue glue"
: Use a "twist and hold" motion when joining the fitting into the pipe to ensure even distribution of the cement. into a pump