GREEN WATER AND INFUSORIA
Taken from the February 1985 TTAA Newsletter
Author: Tommy Sayers, Stanley Aquarist Society 

Many people think green water is an infusoria, this is not quite true, green water is a mass of microscopic plant cells which later forms into the commonly known algae. This can be simply produced by finely chopping some lettuce leaves and placing them in a glass container of tap water, and putting it on a window ledge or similar position in full sunlight.
To obtain both infusoria and green water, use water that has come from a pond or tank containing fish, this will develop within a week, and can be used when necessary.
More chopped lettuce should be used to feed your infusoria. I find it best to remove some of the cultured water and place it into a new container and repeat the process. This will keep you in a good supply of lettuce infusoria for as long as you require.
Infusoria can be made from many things, such as Biol, and Liquifry, which is on sale in your local aquarists shop. I have also- used dry banana skins, condensed milk, boiled hay, chopped maggots, raw meat, raw fish, chopped and freeze dried tubifex, duckweed and lettuce, they all produce a very good infusoria. The one I prefer is chopped tubifex as this gives a very fine infusoria, which can be seen as a moving cloud of microscopic, oval shaped creatures, one hundred times smaller than newly hatched brine shrimp.
As many kinds of fish fry are unable to take freshly hatched brine shrimp at the free swimming stage, because their mouth’s are too small, I feel this may account for many deaths by starvation, rather than disease or any other cause. For fit and healthy fry, green water and infusoria are a must and should be used as a very first food.