Mike: quite intriguing. algae in stream or river?
Peter: Most of my work is in-camera motion movement, unless otherwise stated. The firs is a simple circular motion; the second is a double exposure with two downward motion shots, slight offset. Depending on how fast the shutter speed you may need a little sharpening. Excessive blur, timing and placement of subject are the biggest issues in this kind of Photography.
Early spring is one of the best times because you get both colour and simpler designs in natural subjects, like trees, flowers, shrubs, etc, oft against a simple green background.
JR