Algaecide for outdoor pond?

Hello! I just set up a new pond to start off a monster fish comm but because it's outdoor, the water is always green with algae. I'm using this Japanese brand Algaecide but it only comes in small packets and it's too costly and can't keep the algae away for long

Anyone has any Algaecide brands or products to recommend? Will be greatly appreciated!

Thanks!


Cheers!
Ang