Ted's 6,000 Koi pond in March 2004.  The measurements are  25 ft. by 15 ft. by 4-1/2 ft. deep. The pond has a 20 mil liner with a synthetic fiber carpet underlayment; cotton will deteriorate in one season. 

Mechanical filter is composed of 3 Rubbermaid 300 gallon stock tanks use to accumulate debris which settle out prior to reaching the fiber filter screens.

Biological filtration unit is composed of 1,000 lbs of volcanic or landscape rock. 

For several years pea green algae was a problem.  When the surface was nearly covered with hyacinths visibility was somewhat improved however; plant debris constantly clogged the filter.  Within 2 weeks of adding a 60 watt Emperor Aquatics UV, the water clarity was perfect.  Three pumps with a combined flow rate of 5,400 gph  return the water to different areas of the pond to facilitate good circulation.