I have a 100g tank, with an external canister filter that has a little over 6 feet of flexible clear plastic tubing for the intake. This tube keeps getting algae growing on the walls, which due to the water flow breaks off and clogs the attachments at the top of the filter. This dramatically slows down the flow rate of my filter and I believe is causing my fish to keep getting sick due to poor filtration. Other than getting a second filter (which I think I might put in an internal filter too anyway) how can I stop the algae growing inside the tube and clogging the pipe. I am having to clean it at least once a week because there is bugger all water coming out of the filter. Since algae needs light to grow, would wrapping the tube in black electrical tape be enough to stop it or something else? Does algae not attach to other materials that you are all using on your filters?