i might answer my own question, but I'm having a real hard time with water clarity. I have two large, old maples that contribute debri in the form of whirly copters, leaves, and those darn red bud things. Some is caused by mulch. I have 6/6-7" shubunkins and 8/3-4" shubunkins and koi in approximately 1500 gallon pond. The water is nearly always tea colored. I'm running what appears to be a fairly typical bio-balls filter. So far, I have taken the following steps: netted the pond in fall and spring during peak fallout periods, net any debris I can, and have pulled back any mulch to keep it out as much as possible. I've increased the number of bio-balls 100%. I regularly rinse the mesh screens and filter balls. I also have been running a good sized aeration pump. Lastly, I've been treating it with a product called, "Pond-zyme, with barley". I live in Northern Indiana, so I currently have no plants. Any and all suggestions are appreciated.