"Ideal for fish productivity is visibility in the 18" - 24" range, due to plankton rather than suspended sediment. "
Theo,
When you say sediment are you meaning clay? As I understand it, soil is composed of various percentages of sand, silt, and clay. Sand and silt particles are too large to stay in suspension. Even clay will settle out pretty quickly if the water chemistry is right.
Then, after the water is clear, the whole fertility, algae, plankton thing comes in?
Guess that I'm just asking whether muddy ponds need to be cleared to ever get to that ideal?
