Researchers studied the effects of twelve types of water plants on cleaning sewage in pot experiments. They found that the plants were able to remove over 95% of nitrogen and over 85% of phosphorus from the sewage when given enough time. Some plants, like Lythrum salicaria and Iris pseudacorus, were particularly good at absorbing nitrogen and phosphorus, leading to their growth. Overall, Acorus calamus and Lythrum salicaria were the most effective at cleaning both nitrogen and phosphorus from the sewage compared to the other plants tested.