The researchers studied eight types of underwater plants to see which ones are best at cleaning up suspended solids in water. They found that Elodea nuttallii, Potamogeton crispus, Hydrilla verticillata, Myriophyllum spicatum, Potamogeton malaianus, and Najas graminea are the best at adsorbing solids. P. crispus and H. verticillata are the best at helping solids settle to the bottom of the water. Vallisneria natans is also good at this, but Ceratoplyllum demersum is not as effective. So, if you want to improve water clarity, choose P. crispus and H. verticillata.