Hi Superio,
I have a 1/5HP Artica chiller and usually servicing is done by the service engineer provided by them.
I think it is about S$45. Previously I have two free maintenance but now it is charged.
Anyway for the tubing with black brown algae, it can be ignored as I don't think it is harmful to your tank occupant.
But if you like to clean them, then I would suggest stuffing some tissue that can be inserted into the tube,
and push it out by using a stiff hard stick - long enough to push out the tissue from the other end.
As for the chiller service, if I am not wrong, what the service person did was to take out the cover, and vacuum what ever
visible cotton like dust out of it, and this make your chiller last longer. Well he suggested every 6 months to do such vacuuming,
but as for me, likely to be more than that or whenever I am not comfortable with the sight of cotton dust hanging around the chiller
cover or any opening/ lourves.