Walstad Method – Basics

I discovered the Walstad Method in early 2018. I had kept basic aquariums for several years at that point, and I wanted to try something new. I saw a lot of beautiful aquascapes on Pinterest and I though it would be fun to try out. As I researched it more, I realized how expensive it would be to set up and difficult to maintain (think filters, heaters, chemical additives…). As I searched for an easier and cheaper method, I came across two excellent forums:

Through these two forums, I discovered something I hadn’t heard of before: the Walstad Method. It intrigued me because a mature Walstad tank functions as a nearly complete ecosystem – water changes were nearly nonexistent, and the only tank additions needed were fish food and water to replace the evaporated water. Many of these tanks got a water change every 6 months but that was it. I decided to try it out. First, I purchased and Diana Walstad’s book, “Ecology of the Planted Aquarium.” It was a ton of information and I definitely skipped through some of the more scientific parts. Luckily, the majority of the book was easy for me to understand even without a strong biology/chemistry background.

I definitely recommend reading the book before you attempt a Walstad Tank, but here are some basics for quick reference. You can also refer to my 5gal Tank Setup and 2gal Tank Setup for examples of how to get a Walstad Tank going.

The Walstad Method – my notes from the scientific treatise

Planning: Choosing Tank Size

  • Diana Walstad said that small 1 gallon bowls and 2-10 gallon tanks are perfect for first-timers. Smaller tanks are a great way to find adaptive plant species and learn how to work with soil. In addition, excess plants from a small tank can be later used to start larger tanks.
  • Don’t jump straight to a 10gal or bigger, I wouldn’t go larger than a 5gal starting out. There is definitely a learning curve, and having a smaller tank to work with helped me to learn without being overwhelmed by the initial maintenance.


Planning: Tank Stands

  • Diana Walstad recommends putting a cushioning piece of wood or pressed fiber-board between the stand and the tank bottom, especially for larger tanks (>20gal). The board insulates the tank bottom from cold air and prevents stresses that can cause tank leaks later.
  • I haven’t done this yet, but I’m keeping it in mind for when I have larger tanks at some point.


Setup: Substrate

  • Diana Walstad recommends setting up the tank bottom with two layers of material. The first layer is one inch of unfertilized soil, she recommends Miracle Gro Organic Potting Soil. The second layer is no more than one inch of gravel. The gravel used to cover the soil should be fairly small (2-4 mm). Though sand works okay, she advises to not make the sand layer deeper than 0.5-0.75 inches (sand is a tighter seal than gravel, which can “suffocate” the soil layer). She warns never use stones or pebbles, and make sure the gravel/soil layer isn’t too deep since this will make the soil become severely anaerobic and kill the plants.
  • In my experience, there are two things to really pay attention to here. First, make sure soil and gravel thickness is correct. I did 1 inch of soil and 0.75 inches of fine black gravel. The second is to make sure you fully cover the soil layer with the gravel and not have any thin spots. As the soil breaks down, it will release gas and if your gravel layer isn’t thick enough it will get past it and make the water cloudy.


Setup: Plants

  • Diana Walstad recommends putting as many quick-growing plants as possible into a tank when it is first set up. Remember, Walstad Tanks need tons of plants for everything to cycle correctly. Diana Walstad recommended the following plants in an interview with aquariss.net:
    • Fast, quick growth:
      • Amazon Swordplant (Echinodorus bleheri)
      • Echinodorus major
      • Pygmy Chain Sword (Echinodorus tenellus)
      • Echinodorus “Ozelot”
      • Dwarf Sag (Saggitaria graminae)
      • Grass-leaved Arrowhead (Sagittaria graminae)
    • Take longer to establish but then grow well:
      • Anubias nana
      • Cryptocoryne wendtii
      • Java Fern
    • Best floating plants:
      • Water Sprite (Ceratopteris thalictroides)
      • Frog Bit (Limnobium laevigatum)
      • Others: duckweed, water hyacinth, water lettuce, salvinia
    • Stem plants:
      • Bacopa monnieri (water hyssop, brahmi, thyme-leafed gratiola, herbs of grace, Indian pennywort)
      • Rotala rodundifolia
  • Diana Walstad highly recommends utilizing floating plants, since this will bring more oxygen into the tank. She says they are an excellent way to combat algae.
  • In my experience, pet store plants are poor quality. Even my LFS plants aren’t great. Online is the way to go – ebay has some excellent aquatic plants available with free shipping if you purchase enough. A good rule of thumb is $20 worth of cheap plants per gallon of water. So for my 5gal tank, I spent $100 on plants. You want the tank to be heavily planted, especially at first. Don’t go for the fancy/pretty plants when you are just getting started, go for bulk.
  • As far as the actual planting goes, very carefully add about 2 inches of water to the tank. Don’t displace the gravel layer, since that will release the soil and make the water dirty. If you do it correctly, the water should be crystal clear. To plant the aquatic plants, first do a quick internet search on care to make sure you are planting them in a way they will thrive.For the types that need to be actually planted in the substrate, I \gently push them into the substrate and then brush a thin layer of the gravel on top of it to ensure the soil layer is still fully sealed.


Setup: Filling with Water

  • Word of advice here – do it slowly and carefully! If you pour the water too fast then you will displace the gravel layer and the soil will get through and make everything super cloudy. The easiest way I found was to use a small cup, held upside down, to separate the flow. Place the cup partially into the water you already have in the tank from planting, and then gently pour more water on top of the cup until the tank is full.
  • Once you have the tank full, make sure to add water conditioner to ensure there aren’t harmful chemicals in the water.


Setup: Lighting

  • This is extremely important – in order for the plants to function as filters they need to have adequate light. In most cases, the lights that come with aquarium sets are absolutely insufficient.
  • Diana Walstad recommends 1-3 Watts/gal for a CFL, with temperature between 5,000-7,000 K. The timing of lighting is very important too, Diana Walstad recommends getting a light timer and setting it to a 5hr-4hr-5hr-10hr on/off/on/off cycle. This creates significantly more plant growth.


Setup: Adding Fish

  • Diana Walstad says you are able to add fish right away once the tank is set up. However, many others in forums I have read advise against this because of ammonia spikes that happen as the tank begins cycling. My “middle road” experience is to test chemical levels the day after and if the parameters are looking good, add the fish. Then, I test the water every day for a week to make sure I have spikes under control. After the first week, I test the water parameters every week or two but I haven’t really noticed any chemical spikes.
  • Though you obviously don’t want it to get this far, having freshwater shrimp in a tank are a good parameter indicator. Shrimp are sensitive to parameter changes so if your shrimp start dying then that is a good indicator that something is wrong in the tank. You will want to act quickly if this is the case so that you can correct the issue or remove the fish/shrimp while the issue is being resolved.


Ongoing: Maintenance

  • For the first week or so, I recommend checking water parameters every day. After that, on a weekly basis is fine. My experience with algae is that the tank looks really good for the first month, then an algae bloom happens in the second month. While you are seeing algae, you will want to do nearly full water changes every week and gently remove as much algae as you can with each water change. Another note – don’t try to keep the aquarium squeaky clean, especially if you have snails and shrimp. You need to leave some food for them too.
  • Notes from Diana Walstad:
    • Water changes – change about 25-50% of water every 3-6 months in well-established tanks. New setups may require frequent water changes, because freshly submerged soil releases tons of nutrients
    • Gravel cleaning – cleaning gravel in planted aquariums prevents nutrient replenishment of the substrate. Don’t do it.
    • Filters and water movement – tanks with soil layer and healthy plants will remove ammonia naturally, so bio-filters aren’t necessary. Large deep tanks (50+ gallon) can benefit from a filter, use inexpensive submerged filters.
    • Charcoal filtration – routine may be detrimental, because removed DOC (dissolved organic carbon) that provides CO2 for plants. However, fresh charcoal can quickly remove any dangerous organic chemicals (herbicides, etc.) and can remove excessive water coloration from tannins (which absorb light and can limit plant growth).
    • Airstones – should only be used if the fish are showing distress or gasping at the water surface. In new tanks, a highly organic substrate (fresh potting soil) may pull oxygen out of the water. Only other time to use it if the tank has lots of emergent and floating plants because CO2 degassing won’t inhibit them (those plants get CO2 from air, not water).
    • Pruning, thinning, and transplanting- remove excess growth to allow for fresh growth and water nutrient uptake. Snip off outer, older leaves of larger Swordplants. Pinch off leaves of Cryptocoryne. Try not to cut aerial growth of emergent plants. Thin out floating plants as needed. Don’t prune excessively, that can cause algae problems.


And there you have it! Overall, the process is really easy. Though this post is a great resource if you are setting up your first Walstad Tank, please read Diana Walstad’s book first. There is a lot more information available that is important to know. Here’s a link to Amazon to purchase the book: Ecology of the Planted Aquarium

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