I use a set of these. i run the long one in just past where it's visible. it'll snake through the bend of a lily pipe, just takes a little effort. But i also noticed it's algae related, so the better i do at handling it, the less i have to clean the tubes. My inlet pipe has no space for these brushes, but i noticed covering them for a week or two cleaned allowed the algae to get washed away by the flow.
I bought this set of brushes for just this purpose, and they’ve made tube cleaning a breeze.
Here’s the link to them on Amazon.
Warm water and bleach soak a while. Then rinse well. I also have a brush that’s on a flexible wire like thishttps://www.amazon.com/Aquarium-Flexible-Bristles-Stainless-Different/dp/B07PGFDY7R/ref=mp_s_a_1_3?crid=3MGJGTGY9XJD9&keywords=brush+for+aquarium+cleaning&qid=1665439933&qu=eyJxc2MiOiIxLjk1IiwicXNhIjoiMS4zNyIsInFzcCI6IjAuMDAifQ%3D%3D&sprefix=brush+for+aq%2Caps%2C77&sr=8-3