Pond Maintenance Package (1lb Hornwort and 10 Trapdoor Snails) Increase Water Quality and Fight Algae Japanese Trapdoor Snails (Viviparus malleattus) will help keep algae in check and will reproduce quickly Hornwort (Ceratophyllum demursum) is a fast growing, low maintenance, low light plant that will help increase water quality while giving fish shade and possibly places to reproduce. Hornwort is a naturally floating plant and should be anchored if there is a fast moving current for overflows or filters We recommend this package to ponds up to 3,000 gallons The only thing we'd recommend adding would be mosquitofish