If you are trying to grow wetlands or bog plants in containers, chances are those containers are sitting in bowls of water. While most plants prefer not to have wet feet, bog plants such as cattails and lotus prefer these conditions. But as plants sit in water, the water can build up bacteria and algae. One method for killing bacteria in cut flowers is to add bleach, but this should never be done to potted plants. Instead, consider adding a water bubbler, such as the kind used to keep pet water clean.
Put your plants in a bowl or other large container.
Fill the container using distilled water, rain water, or boiled water. This water is free of bacteria to start with. Starting with a bacteria-free environment can stall the growth of bacteria in the water.
Purchase a small aerator such as an aquarium bubbler.
Place the aerator pump on the lip of the bowl to keep the water in the bowl circulating.