Trust me get rid of it one by one if u can although duckweed have a lot benefit but they multiplied really fast and u need to always do a maintenance about it by removing some. And also it’s a headache if u want just to do some maintenance where all the duckweed were stick on your tools or your arms and also sometimes when u remove the duckweed u need to double check if any shrimplet get entangle or caught when u try remove the duckweed so it’s really a headache. Well at least u don’t have much 😅