I have just completed major installation in Hanford. The appx 20k gal total volume, the pond was built with settlement chamber and japanese mat chamber as inline filtration. These chambers are huge (under the boards) They measure appx 8ft deep, 10 ft wide and more than 20ft long, they hold almost as much water as the pond itself. The owner was never happy with the result. Water was always murky during heavy feeding season and the chambers couldnt provide. With the intention to aid clarity, there were add-ons of bead filters, sand/gravel, home made showers, patches work here and there. All these had to go.