How do I clean this green algae?

[Alon Y amin]

Hi,I have a 4000 liter pond with koi and goldfish, I build my filter with tubing and a barrel with lava rocks, I have a 36w uv system and a 12,000 lph pump running 24 hours a day.
How do I clean this annoying algae from my waterfall and filter?
Also the green algae floating in the pond shows up in the day and disappears in the night.
I’m attaching some pictures, please replay

 

[MitchM]

Alon, the buildup of existing algae and dead algae that is accumulating in your blue barrel is decomposing and re-releasing nutrients into the water, contributing to further algae growth, which will be an ongoing cycle until you physically remove the buildup from the barrel.
Perhaps you can remove the accumulating material from your barrel and deposit it into your garden or compost it somewhere.

 

[Mmathis]

Hello @Alon Y amin! It’s been a while since we’ve heard from you. Just curious, but what was your solution to the “noisy” waterfall situation (where your Mom thought it was too loud)? And how has your pond been doing?