I agree with what most of wetman said. The filtration isnt NEARLY as good as our tanks or the Ocean. So its murky.
There is a cure though. Add Zebra Mussels (not really.. it will destroy that ecosystem). In some of the Great lakes (not sure which), people would say they could see a foot into the lake before the mussels invaded. After the invasion, the lake was Crystal clear. Problem is the fish in the great lakes arent very popular to photograph...Now if it was any of the Rift lakes, the Amazon, or the Nile, then there would be MANY photos..