request number 5,224 for the minimum specs for a proper koi pond. "Search" function will let you find a thread here discussing that. I'm too feeble and inept to put a clickable link right here for you, sorry. Good luck.
Birdman, for 5000g of flow the required settlement chamber is 1,250 gallons.
This is a big factor in the popularity of the static filters like Eazy.