(1) The best bushy plant is Egeria or Elodea densa.

(2) Sweden could use Elodea collagen.

(3) Through the above studies, the following conclusions were gained:(1)Elodea nuttallii can survive through a year and the maximal biomass appears in autumn.

(4) The purification ability of Elodea Canadensis Michx is higher than those of Potamogeton Crispus Linn and Ceratophyllum Demersum Linn.

(5) Because goldfish will eat new plant growth, use fast-growing varieties, such as Elodea canadensis, Ludwigia and Vallisneria.

(6) Examples include filamentous algae such as Spirogyra, and waterweeds like the Canadian pondweed ( Elodea ).

(7) The potential problem of secondary pollution due to the decomposed Elodea Canadensis Michx was also discussed.

(8) It is showed that the gradually-submerging bed made of plant fiber, Potamogeton crispus and Elodea nuttallii can grow in low temperature condition in winter.

(9) In a given range of biomass with the increase of biomass, the water improvement effects by Elodea nuttallii , Potamogetor crispus and Hydrillaverticillata become more obviously.