flow in 20g tall

I have a 20g planted tank. I currently have 6 Tetras in there, 1 cherry shrimp, and 1 red crystal shrimp. I plan to add about 6 more Tetras, that's it.

My drop checker is consistently a yellow-green, and I run CO2, I do weekly water changes (about 20%), change the carbon, and rinse everything in my canister filter 1x / month.

I have some black 'filmy' algae that gets on some of the plants, the driftwood, and partially on the bottom. I siphon as much as I can during water changes, but it still comes back.

Would adding more flow help?

I am looking at this pump, and would like to know your thoughts.

https://reefbuilders.com/2014/04/03...llery/6c79a601504c620b9a08836b5cd16e6a/10768#