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What is the Walstad Method?

You may have heard me speak about the virtues of a Walstad- style aquarium before, but what is it exactly? Why are they so great for beginners? For someone with less time to dedicate to maintaining a tank? Or even someone who loves the science behind this complicated little ecosystem behind glass?

This guide is about the Walstad Method for freshwater aquariums, a system that uses soil substrate to grow plants, which then filter water for your livestock to live comfortably.

Once your aquarium is established and matured, you can achieve stable growth of easy-care plants with minimal work and maintenance. Yes, truly!

The Walstad method was designed and popularized by Diana Walstad, and explained in detail though her book (Ecology of the Planted Aquarium: A Practical Manual and Scientific Treatise for the Home Aquarist)

As a North Carolinian biologist and aquarist, she set out to design indoor aquatic ecosystems that work harmoniously and with low keeper intervention to ensure the health of plants and fish within a more natural ecosystem.

For more on her science, including articles on planted tanks, fish diseases, and Guppy breeding, have a look at her website here.

Tanks built according to her guidance and methods notably do not use carbon dioxide injection. The plant's sources of essential nutrients come mainly from the soil substrate, and fish and their waste, rather than external human intervention. 

No matter the size, these types of heavily planted aquariums are often thought of as 'Jungles', and 'overplanted' (as if there were such a thing!). The bounty of plant matter serves many important purposes here, however!

By heavily planting, the aquarium works as a fully isolated ecosystem, leaving the hobbyist with only two regular tasks:

  • To feed their fish, and;
  • Refill any water that has evaporated.

The vast majority of planted aquariums these days use a filtration system and filter media, constant water changes, a plethora of chemicals, fertilizers, supplements, and various other agents.

We haven't even gotten into what is needed for an even more high-tech tank with Carbon Dioxide injection!

All that equipment for a conventional tank is responsible for supporting the inhabitants' lives, by keeping the water in perfect condition, always.

With the Walstad Method, there is not much in the way of equipment and supplements. A light is needed of course, but usually no heater, airstone, or even a filter.

To keep the aquarium healthy, you have to feed the fish and replenish the water; it's basically filling the aquarium with water and leaving the fish and plants to do their thing.

You'll need to put a little thought into the types of fish or invertebrates you'll stock your aquarium with.

Most tropical fish can comfortably be kept in water between 67 to 80 degrees Fahrenheit. This just so happens to be the room temperatures people are most comfortable at!

White Cloud Mountain Minnows are an excellent choice, as they thrive in unheated planted tanks!


Walstad aquariums offer something different from a conventional tank with a regular old gravel substrate. They also shun the use of expensive specialized substrates-- Instead, the most popular Walstad base for your tank is simple organic topsoil, and a layer of sand.

The use of simple soil provides almost everything that aquarium plants need-- and the fish, through their excreta and metabolites, can supply the rest of the nutrients.

At the same time, fish thrive thanks to the plants' ability to filter pollutants from the water, leaving the water in perfect, balanced condition.

It is a simple, intuitive system, incredible in itself and unmatched by any other method we know within the aquarium hobby.

Aquariums that use this method are a living example of the interconnection of plants and animals.

Best of all, once everything is cycled and balanced, the system requires very little maintenance.

Personally, my Walstad tanks need very little. Most go without water changes for six months or longer. I still recommend testing your water here and there to head off issues. 

In general, the less you worry and fuss with it, the better... just like in nature.


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