cultivating live food in a sump

I know many people cultivate food in saltwater sumps but are there any live foods you can cultivate in a freshwater sump?

 

Blackworms might work?

 

TexasDomer how would you go setting it up

 

Daphnia may be an option too. The issues you'll run into with keeping any live culture in your sump is keeping it clean so as to not dirty the main tank.

 

Ive tried chucking live daphnia in my sump hoping they wiuld feed on what was in the filter but they never get established

 

They need a lot of aeration and movement if I'm not mistaken.