Dark dirty pond

Question
Help please! We have a 5000 gallon hand made pond with a brand new liner this spring plus 6 large koi and a few small ones plus toads that come.  We have a new Sanio large skimmer and a large bio filter and a pump that we are told turns over the water once per hour. The problem is our pond appears to have a cloudy brown color even after it was just emptied and pretty much cleaned because of caterpillar poop dropping from our oak trees over the edge of the pond but they are now gone and changed into moths.  When we first filled it again after cleaning it about a week ago it was clear with just a little brown tint but then got cloudier as each day went by so I assume when I cleaned it did get clean enough. We also have 5 gallons of activated carbon in the bio filter with coke rock to remove any tannin in the water that could be staining the water from the oak leaves.  It doesn't appear that much is dropping in the pond from the oak tress right know. The pond looks clean from anything floating like leaves or sticks etc. and the edges of the pond are raised way above ground level with cinder block under the liner so I am certain nothing is running in. Do you have any thoughts on why the water appears cloudy?  I can see a light sprinkle of what appears to be dirt on the rocks in the water but just cannot figure out where it is coming from or what it is but don't know that this is causing the cloudiness cause it is settled on the rock.  Any ideas would be greatly appreciated?  Thanks so much.

Answer
Hello Brenda!
Has it rained lately? I know I used to have a problem with a cloudy pond because the dust from the leaves of the tree next to it would wash into the pond.
You may have to use some extra filter matting in your skimmer and a flocculant (like Sheer Clear or Accu Clear) to bind the stuff so the matting can pick it up.
Brigitte
www.pondmarket.com