Floating Aquatic Plants Much of the attention in natural wastewater treatment systems has focused on floating aquatic plants. Water hyacinths are especially attractive for wastewater treatment. Water hyacinths produce a unique ecosystem which improves wastewater treatment efficiency. Hyacinths usually cover an entire basin, lowering water temperatures, reducing wind action and limiting algal growth.
Some hyacinth systems suffer from mosquito problems.
When using Gambusia, aerated zones should be provided where the fish will receive sufficient oxygen. Toxins should also be monitored to avoid fish kills. This may be a concern for cities required to provide return flow for downstream users. NASA research also indicates that hyacinths and pennywort remove significant amounts of heavy metals and toxic chemicals. Toxins were metabolized by microorganisms on plant roots, and heavy metals were concentrated in plant tissues.