I straighten out a coat hanger, then make a small loop on one end with needle nose pliers. Hook the looped end of the brush around the hanger and crimp the hanger loop. Make a 90 degree bend in the other end of the hanger wite. Now you can turn the brush and pull it back and forth in those long tubing runs. I've cleaned my Eheim cannister tubing this way for years.
Get a sufficiently long piece of string (butcher's twine). Tie a wieght to one end (nut, bolt, nail, whatever...). Tie a small patch of cloth to the other end. Drop the weighted end through the tube and pull the cloth patch through.
Most of the crud that builds up in the tube won't require much effort to wipe off. For algae, soak the tube in a 5-10% bleach solution first, then run the patch through.