You may have heard us saying time and again on our website that betta fish always need a filter, and need their tank cleaning regularly. For a typical betta aquarium, this is completely true.
But even the best rules of thumb have their exceptions, and even advanced aquarists may be surprised to learn that there is a type of tank that you can set up to clean itself.
Introducing The Walstad Method! A heavily planted aquarium setup where the plants and microorganisms do the cleaning and keep the water in a healthy equilibrium.
Be warned though, this method is no quick fix for the lazy fishkeeper! Setting up a self-cleaning fish tank is hard work and takes a lot of knowledge and understanding of the delicate balance between all the organisms and the chemistry of the tank.
In this article I’ll take you through a step-by-step process of how to set up a DIY self-cleaning betta tank using The Walstad Method (recommended for experienced fish keepers only!).
Who Is Diana Walstad?
Diana Walstad lives in North Carolina and is the author of the book ‘Ecology of the Planted Aquarium’ and technical advisor for the AGA (Aquatic Gardeners Association). She developed the Walstad method of setting up and maintaining a heavily planted aquarium with minimum intervention from the aquarist.
What Is the Walstad Method?
The Walstad method is a system of creating a largely self-sustaining aquarium where no filtration and very infrequent water changes are made possible by utilizing plants and microorganisms to create a healthy miniature ecosystem.
Once established, the plants, bacteria, and organic substrate are capable of keeping the tank ecology in a healthy balance and performing the majority of aquarium cleaning and maintenance for you.
What Are the Advantages of a Self-Cleaning Planted Aquarium?
Apart from doing most of the cleaning work for you, creating a natural self-cleaning aquarium with methods similar to those outlined by Diana Walstad can be a tremendously rewarding venture.
Instead of using modern filters, chemicals, and methods, the fish keeper puts their faith in nature to create a self-sustaining aquarium ecosystem that can regulate itself perennially.
There is something immensely gratifying about organic methods like this, where you can witness the marvel of nature doing its work to create ideal conditions, just as it does in the wild.
Aquascaped aquariums are also incredibly beautiful, and can be made to resemble the densely planted habitats that your fish species come from in the wild.
What Are the Disadvantages of a Self-Cleaning Planted Aquarium?
One of the reasons that self-cleaning planted aquariums haven’t become more popular is that they require quite a lot of skill and know-how to set up and maintain.
With a regular aquarium, you simply follow the basic rules of cleaning your filter, vacuuming your gravel, and making partial water changes, and nine times out of ten, your water quality will be relatively good and your fish will remain relatively healthy.
An aquascaped tank without a filter requires a much deeper and more subtle understanding of the aquarium ecosystem and how it interacts with water parameters and your fish’s well-being.
For these reasons, I would recommend this type of setup for intermediate and advanced aquarists only. If you are a beginner, I’d strongly advise you to get at least a couple of years of basic aquarium maintenance experience under your belt before attempting a self-cleaning aquarium setup!
How To Set up a Self-Cleaning Betta Tank Using the Walstad Method
If you feel you have the necessary experience and commitment to attempt a self-cleaning planted tank, here is a step-by-step guide on how to create it.
Step 1: Choose Your Tank
The first thing you’ll need for your self-cleaning betta aquarium is a fish tank! While bettas can be kept in tanks as small as 5 gallons, these types of nano tanks are notorious for having unstable water parameters and are unsuitable for the self-cleaning method.
I’d say 10-gallon aquariums are the absolute minimum for a filterless aquascape tank, and 15 or 20 gallons would be much better. Larger tanks have more steady water parameters and also allow you more room to include a clean-up crew of fish and invertebrates that will help to keep your water clean.
Step 2: Choose Your Tank Lighting
Self-cleaning aquariums rely on vigorous plant growth to purify the water. For vigorous plant growth, you’re going to need the best possible lighting for your tank.
Put your lighting on a 12-hour day: 12-hour night cycle, or another of the various cycles recommended for planted tanks by using a lighting timer switch.
To find out more about finding the ideal lighting for your planted tank, be sure to check this handy guide.
Step 3: Place Rocks To Create Bottom Contours
The next important consideration for healthy plant growth is to have enough soil at the bottom of the tank for your plants to thrive.
You could place a uniform depth of soil over the entire aquarium and cover it with gravel, but this flat bottom contour has less visual appeal and also will reveal unsightly soil against the glass at the front of the tank.
A more interesting approach is to arrange rocks at the back of the aquarium to create one or more raised tiers that can be filled with soil and substrate.
Arrange your rocks to fit together as tightly as possible, and then use aquarium filter floss to pad out any gaps to prevent soil from spilling through.
Step 4: Choose Your Organic Soil Substrate
Next, you need to add your soil substrate. Unlike regular aquarium soils, however, this method requires an organic approach.
The fertilizers present in aquarium soils are too rich and volatile for this no-cleaning method where a balanced water chemistry is key. Also, note that soils and composts containing peat will make your water softer and more acidic.
Diana Walstad recommends the following soils as the ideal substrates for self-cleaning tanks in the USA:
- Scotts Lawn Care – Hyponex Potting Soil
- Scotts Lawn Care – Miracle Grow Potting Soil
- Scotts Lawn Care – Miracle Grow Organic Choice Potting Soil
In Europe, she recommends:
- Miracle-Gro – Organic Choice All Purpose Peat Free Compost
- Miracle-Gro – Organic Choice Premium Garden Soil
Step 5: Add Your Soil
Now carefully place your chosen soil in the tank. Diana Walstad recommends using a one-inch layer, but if you’re going for the contour approach, you could use a deeper layer at the back of the aquarium, and none at the front.
Break up any lumps, and lightly poke the soil down with your fingers to ensure the soil’s settled in and that there are no air pockets.
Your soil should provide adequate nutrition for your plants and important dissolved trace elements for your fish for the next 10 or so years.
Step 6: Add Medium-fine Gravel
Before you add your water, you need to make sure your soil is completely covered so that it doesn’t muddy the water. Choose a sustainably sourced medium-fine gravel, and cover the soil with 2 inches of it.
For this system to work, the soil needs to breathe, so there must be adequate ventilation between the gravel pieces. If you prefer using sand or a very fine gravel, only add a very thin layer.
Never cover the soil with large rocks since they won’t provide sufficient gas exchange for it to remain healthy.
Step 7: Add Driftwood and Other Tank Decor
There’s something about driftwood that looks especially beautiful in an aquascape fish tank. Hardwood, driftwood and woody roots would also be a common feature in a betta fish’s natural environment, and release tannins into the water that many people consider to be beneficial to a betta fish’s health.
Another element that you can add that contains tannins are Indian almond leaves. For the natural-looking aquascape aquarium, some leaf litter on the aquarium floor can add to the aesthetic, and many aquarists have reported health benefits from the addition of these leaves that have reputed medicinal virtues.
Note that carbon filtration will remove tannins as well as the amber color that they infuse the water with.
Step 8: Add Treated Water
Now that all of your soil is covered, you can fill your aquarium with treated tap water. Make sure that all of the chlorine and heavy metals have been neutralized by using a specialist aquarium water conditioner.
If you already have another established healthy fish tank that’s free from pests and diseases, you can give your new aquarium’s ecology a huge head start by adding 30-40% of the water from your existing tank.
Step 9: Add an Aquarium Heater
Although this type of tank is very low-tech, betta fish are tropical fish from near the equator and still need an aquarium heater. Their required water temperature range is 78-81°F.
To learn more and see our recommendations, check out our guide to heaters for betta tanks here.
Step 10: Add Plants
Now, the fun part! Choose your plants. To start this type of tank, you want to choose species that grow fast and powerfully clean the water and produce an abundance of dissolved oxygen.
Plant your tallest plants at the back of the aquarium, medium-sized ones in the middle, and short plants in the foreground. Consider some floating plants to create a dappled shade effect, and be sure to leave some open water swimming space for your betta in the center of the tank.
Please see the end of the article for a list of plants that Diana Walstad recommends for self-cleaning fish tanks.
Step 11 (Optional): Consider Adding a Filter
Because water chemistry in this type of tank can be quite volatile at the beginning, some aquarists using this method will use an aquarium filter for at least the first two months, to help the water’s chemistry and biology to settle in and find its balance.
Step 12: Cycle Your Tank
Now that you’ve added your soil, substrate, water, heater, and plants, it’s time to let your tank cycle. Since you’re already an experienced aquarist, you’ll be well-familiar with the nitrogen cycle and cycling a tank with a filter.
If you’re not using a filter, understand that nitrifying bacteria are encouraged to colonize the substrate rather than the filter’s sponge. These beneficial bacteria powerfully convert toxic ammonia and nitrites into nitrates that are relatively benign and will be kept at low levels by abundant plant growth.
As your plants grow they will gradually balance out your water chemistry and produce plentiful oxygen through photosynthesis. Leave your tank to cycle for at least 2 weeks if you’ve added existing aquarium water, or 4 weeks if you’ve only used treated tap water.
Step 13: Test Your Water
Before you add any living creatures to your tank, you need to test the water to make sure that water parameters are safe and stable.
Ammonia and nitrites should be at zero, and nitrates should be less than 20 ppm.
Bettas need clean water with a pH of between 6.5-7.5 and a dGH and dKH of 3-15.
For the self-cleaning tank to have a healthy ecology and function properly, you’ll need the water hardness to remain above 6 dKH and 7 dGH.
Also, check that your plants are growing well. If they’re not, make sure that your lighting is adequate. Your soil should contain sufficient nutrients, so as long as pH and water hardness are at the correct levels, fertility is unlikely to be an issue.
Step 14: Correct Your Water Parameters
In this type of tank, getting the ideal water chemistry is a fine art that requires practice. As the soil is established in the first two months, you may experience dirty water with spikes in ammonia and nitrites, algae blooms, and fluctuating pH, GH, and KH. I didn’t say it was going to be easy!
To rectify ammonia and nitrite spikes, you can either perform partial water changes or add water treatments to your aquarium such as Seachem Prime which neutralizes ammonia and nitrites.
If your water hardness is less than 6 dKH and 7 dGH, you’ll need to add some type of water-hardening agent such as limestone, sustainably sourced crushed coral, or sea shells until it’s consistently within the correct range.
Keep testing your water. Only when it’s consistently within the safe range can you consider introducing your first invertebrates.
Step 15: Introduce Algae-eating Invertebrates
For this type of tank, I’d recommend adding some invertebrates that can help to keep your tank clean. Shrimp and snails (see list of species at the end of the article) are especially good at removing excessive algae and may be considered less valuable than your precious betta fish to test the water with!
Add these invertebrates to your tank first and keep checking their health and water parameters for another couple of weeks before adding any fish.
Step 16: Introduce Your First Fish
If you intend to keep other fish in your betta tank, I’d recommend introducing them and letting them get settled in before you add your betta fish.
Betta fish (aka. Siamese fighting fish) are notoriously aggressive fish and are often territorial towards their tank mates. This is especially likely if you add other fish after your betta has settled in and established his territory.
By adding other fish first, and allowing them to feel at home, and your betta is more likely to accept their presence in the tank.
Self-cleaning fish tanks, and especially those without a filter, rely on a low-stocking density to remain safe. Try half the stocking density you’d normally go for, and see how things go from there.
Step 17: Introduce Your Betta Fish
Now that your tank is well-established, it’s time to add your betta fish! Since bettas can easily suffer thermal shock from sudden temperature changes, take extra care when transporting your betta to his new home.
If you buy him from a store, place his bag in an insulated box (cooler boxes also work well to keep things warm!) or wrap the bag up in several layers of cloth on the way home.
Float the bag for at least 30 minutes with the lights off to ensure the smoothest, least stressful entry to the new tank.
Step 18: Maintain Your Self-Cleaning Betta Tank
Although you won’t have to do much cleaning in your self-cleaning betta tank, there’s still some fine tuning and a few ongoing maintenance jobs to carry out!
For the first two months, you need to make partial water changes to remove any toxins released from the soil, such as wood oils and excessive nitrogen. After this, water changes can be very infrequent, and you may also (cautiously) be able to remove your filter if you have used one to get things started.
Keep testing your water regularly to ensure all water parameters are within the right range. This is especially important when introducing new fish or making any changes which could tip the balance slightly.
Have some Seachem Prime or another ammonia removal agent on hand in case your tank suffers an ammonia spike.
Step 19: Prune Your Plants
Since this style of no-cleaning aquarium promotes abundant plant growth, you’ll need to trim plant leaves back from time to time to maintain enough open water and enough light for less dominant aquatic plants to thrive, too.
How much you do this depends on personal preference, as well as the mixture of live plants you have chosen.
Once your fast-growing plants are established, you can add slower-growing plant species such as Anubias species and Hydrocotyle verticillata.
Step 20: Adding More Fish
Once your self-cleaning aquarium is up and running, you might consider adding more fish. Be careful with this, as more fish will increase the bio-load and may overwhelm the tank’s ecosystem with all the additional respiration and fish waste.
Filterless tanks are only suitable for low-stocking density aquariums, so consider adding a sponge filter if you choose to keep more fish.
Self-Cleaning Betta Tank FAQs
Which Fish Make the Best Tankmates for Betta Fish?
Bettas are aggressive fish but also quite delicate and need their tank mates to be both peaceful and robust. Good mid-layer companions include rasboras, rainbow mountain minnows, and danios.
Bottom-feeding fish that tend to stay out of the way of betta fish and also keep the tank clean are especially recommended. Corydoras catfish (aka. Cories), bristlenose plecos, kuhli loaches, and Siamese algae eaters are all good candidates.
Which Shrimps and Snails Can I Keep With My Betta Fish?
I mentioned earlier that several types of invertebrates are especially useful for self-cleaning betta tanks because they can help to eat up any leftover food, and excessive algae in the tank.
Cherry shrimp and ghost shrimp make great tank mates for peaceful betta fish, although their prolific breeding can also get out of hand!
The larger Amano shrimp don’t breed in freshwater and are probably the best algae eaters of any shrimp species!
As for snails, nerite snails are a popular choice because they do a fabulous job of eating algae and don’t breed in freshwater. If you don’t mind having lots of snails, then mystery snails and Malaysian trumpet snails are also an option.
(Bear in mind that betta fish vary wildly in their temperaments! While some bettas may live quite happily alongside guppies and tetras, others will attack any tank mates including shrimps and snails!)
Which Plants Can I Keep in a Self-cleaning Betta Tank?
When you’re first setting up a self-cleaning aquarium, you want to add plants that grow very quickly that will filter waste and produce plentiful oxygen in the water. Once the tank is established, you can add slower-growing species.
Diana Walstad recommended the following:
Fast, Quick Growth
- Amazon Sword Plant (Echinodorus bleheri
- Echinodorus major
- Pygmy Chain Sword (Echinodorus tenellus)
- Echinodorus “Ozelot
- Dwarf Sag (Sagittaria subulata
- Grass-leaved Arrowhead (Sagittaria gramineae
- Dwarf Baby Tears (Hemianthus callitrichoides)
Plants That Take Longer To Establish
- Anubias nan
- Cryptocoryne wendti
- Cryptocoryne balansa
- Java Fern
Best Floating Plants
- Water Sprite (Ceratopteris thalictroides
- Frog Bit (Limnobium laevigatum
Reliable Stem Plants
- Bacopa monnieri (water hyssop, Brahmi, thyme-leaved gratiola, water hyssop, herb of grace, Indian pennywort)
- Rotala rotundifolia
Setting up a planted tank to clean itself can be a fascinating venture for the experienced aquarist.
If you’re serious about it, I’d highly recommend reading Diane Walstad’s book – Ecology of the Planted Aquarium to gain more in-depth knowledge and instructions.