cleaning grass from duck pond?

[chickadoodle]

Hi, I am having problems with the duck pond as the grass keeps clogging the flow. I somehow need to find an effective filter that will stop the grass but still let the water through. Any ideas please! Many thanks

 

[dorsetduckowner]

Hiya, my pump and filter seems to work effectively, I have to unclog the pump every 3 or 4 weeks and clean the filter every 3-4 months. If it isn't grass it will be feathers!!! What size pond/filter/pump do you have?