information regarding azolla

hello any one please help me to get some knowledge regarding how to grow azolla
till now i have grown azolla at 6 places but still it is not successful.i have read many articles from google.
let me say what i have did if there are mistakes inform me.
i have prepared azolla tank using silapulin sheet, then i added little mud, dung and water then i have added azolla into it.but it is not growing it is becoming less day by day.
any one inform me