walstad1 150x150 A Simple Walstad VesselDumping a couple pounds of garden soil into a fish tank is probably the last thing you’d expect to do when first setting up an aquarium but that is exactly what I did when setting up this “El Natural” aquarium vessel.  The El Natural style, popularized by Diana Walstad in her book, “The Ecology of the Planted Aquarium”, is based on the application of soil in the aquarium to grow healthy aquatic plants and thus achieve that rare and elusive goal of every aquarist: the ecologically balanced aquarium.  Obviously, garden soil is a great nutrient-rich substrate for growing plants.  When placed below aquarium gravel, the soil also acts as a source of CO2- an essential ingredient to healthy and robust photosynthesis.  Plants would grow luxuriously and soak up the nitrogen-rich waste of the fish.   Gone would be the need for expensive CO2 injection equipment. Gone would be the need for constant dosing of plant fertilizers.  Gone would be the need for time-consuming water changes.  A simple but rich-in-promise theory that I was anxious to put to the test.

walstad 150x150 A Simple Walstad VesselIt was a dismal, rainy and cold Fourth of July 2010 in Seattle; my plans for camping in the mountains for the long weekend cancelled.  I decided to cheer myself up by making some magic happen with aquatic life.  I had recently purchased an antique 5-gallon beer carboy at a local flea market.  I had some plants.  I had a compact fluorescent chick brooder light.  I had water (obviously).  I had the time.  I was inspired.  The dirt used for the tank had been “seasoned” through the summer in an old Instant Ocean bucket full of dirt and water outside for a couple months.  Seasoning the soil essentially means to let it sit idle, wet, diluting that first extreme pulse of nutrients released to the aquarium. Fresh soil can lead to algae blooms in an El Natural tank.

walstad3 150x150 A Simple Walstad VesselThe lighting was very intense and by the end of the first week, the tank was opaque with green water.  A solid glowing green. I don’t have a photo of that phase in the El Natural vessel’s life cycle but you can imagine it if you have ever seen a five-gallon jug full of krypton flavored beer.  I changed 75% of the water volume at the beginning of the week and then for a day or so I could observe the fish before it went back to murk again.  This went on for a few months.  Despite the green water, the gold least killifish,Heterandia formosa “Gold” that I placed in the vessel were thriving and breeding.  I suspect the only way the beautiful radiant golden variety of Heterandia formosa can persist in nature and escape the attention of predators is for them to live in deeply murky, green water environments where they cannot be seen.  They must have felt at home in my carboy.

Five months later, the Walstad carboy has reached a gentle equilibrium:  no need to do extreme weekly water changes, gone is the radioactive green water.  The plants are growing well and healthy; I’ve added some red lilies and anxious to see how they transform the aquascape.  Dwarf shrimp also complete the vessel’s animal component; they seem at home and drift around the vessel in constant foraging mode.  Though I found it took a few months to reach its balance, the El Natural vessel has now reached its promise as a low-maintenance aquarium.  No filters.  No heater.  No hassles.  Just water, light and life.

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walstad2 A Simple Walstad Vessel