Just checking my Eheim Ecco, and found the pipes had some sort of gunk in them....Any ideas as to what it could be?
This is my first external and i am still learning.
Can't get away from that - as long as the waterflow is good it's not a probelm. You can give them a hot water flush if it bothers you, but then it can be a pain to prime the filter again.
Weight attached to the string and let gravity thread it through then attach the brush. Tie some string to each end and draw through the pipe back and forth.