CONTROL THE MOTION
Experiment with different shutter speeds to vary the level of motion recorded
When it comes to capturing motion in water there is no ideal exposure, simply because every situation differs. if the water is flowing furiously, you can blur it with a faster shutter speed than would be needed for a gentle stream. The solution, therefore, is to experiment with different shutter speeds to find the ideal one for the scene or subject. Maybe start at 1/30sec, then get progressively slower in 1/3, 1/2 or full stop increments, checking each image as you go. The comparison set of images here will give you an idea of how the effect can be controlled. The one you choose is down to personal preference.