Lilittle Visibility

4200 gal Pond, After the Pond was finished I allowed the water to Filter through the pond 1 month before adding fish, I started with 50 comet Fish, In a week time I saw several of the Comet fish floating, I waited three weeks before buying 50 More Comets. A month past I began seeing little orange fish swiming. I added some water lilies, all the fish disappeared. I thought they all died. I waited several more months before I purchased my first Koi , Aprox. 6", he lived. As time pasted the water started to become cloudy, I Obtained 7 more large Koi. 8" - 12" They seem to be doing good, and the comet I thought died they lived and now I imagne they are running away from the larger fish. I see them all the time on top of the water as I feed them. I do not have a uv light.