Originally Posted by ChoclateBetta
Whoops sorry thought you meant regular tank. What is special about Walstrad method?
The Walstad method uses real organic soil capped with sand, so that dead matter and waste can break down efficiently enough for the plants to eat it quickly. Its aim is to get as close to a closed ecosystem as is possible for a fish tank. Once the tank is established, water changes need to be done much less frequently than your average fish tank, because if you find the right balance of plants and animals, they contribute to each others' needs and do not produce excess waste.
If you've just got a gravel bottomed tank, then once a month changes certainly aren't going to work. With the Walstad method, this is easily achievable.