My Walstad tank

[Molch]

After reading Diana Walstad's book about the dirt-based aquarium, I had to try it myself:

this is my 20 ga tank after 8 weeks. It's a tropical tank with fish. Had a bit of a rocky start with algae and some plants dying, but others have done well and now it seems very stable with almost no algae. I cheated a bit by supplying DIY CO2. I get a whole bag full of clippings out of there every week.

Next, I want to try this with a cold-water tank, say 60 F. If that works fine, I can have my newts in a tank like this one.

It's kinda cool to have a bit of tropical jungle on your desk, with the Arctic winter just 1 foot away on the other side of the window.

 

[Azhael]

Beautiful! I love densely planted tanks

 

[RobM]

Beautiful, I wanted to try this in my aquariums too!

 

[Jennewt]

Beautiful! How long have you had it set up? I'll be interested to see how it evolves over time.

 

[Molch]

Beautiful! How long have you had it set up? I'll be interested to see how it evolves over time.

thanks all! I set it up the first week of December, so it's been 8 weeks. It always looked pretty good, but I had a bit o' green fuzz algae at first, and a few plant species didn't make it. Most of the Bacopa australis died (though one bit survived and is now growing copiously) and all of the Limnophila went belly-up. I had java fern, too, which did well, but I took it out to put in my newts' tank for egg laying, and planted E. tenellus instead.

I also added a handful of snails and 2 algae eating fish. Things really took off when I added DIY CO2. Technically, that's not pure Walstad, but I was impatient and curious how it would make a difference, and I'm really happy with how it improved things. The Anubias, java fern, and Bolbitis only started actively growing and making baby plants after I added the CO2. It's very low-key, just a yeast bottle I replace every 10 days or so, but I get lots of pearling from the plants.

Currently, the water is very stable, plants grow madly, and there is almost no algae, except for a few beard algae here and there which I take out manually.

 

[Molch]

here's how it looked when I first set it up. The feathery stem plants on the left (Myriophyllum and Limnophila) didn't make it and have since been replaced by Vallisneria and Ceraopteris.

The ol' pot has come a long way. I'm curious now to see how it will evolve long-term.

left side with the Arctic sunrise behind

right side; root has since been removed

 

[Molch]

Here is an update on my Walstadian tank. It has gone through quite an evolution.

Sometime after the last pics I posted from when it was 8 weeks old, things went south, haha. At the time, I supplied DIY CO2 (the ol' yeast bottle) and had high light on it (2 26 W CFLs in clamp reflectors). The plants grew like a wildfire. I had to clip them back every few days! In other words, it wasn't really a Walstad tank at all - it was a high voltage, high maintanance Co2 injected tank.

When the Ceratopteris grew so huge it threatened to smother everything else, I went a bit nuts with the pruning shears and clipped back the plants severely (to about 50% of their biomass). At the same time I took the CO2 away and cleaned the filter. Baaad idea: too many changes at once (I DO know better, so don't ask me why I did all that). Next thing I knew, the entire tank was choked by green mat and green string algae. Yuck!

I kept pulling about a pound of algae sludge out of the tank every week and was about to give up and tear the whole thing down. As a last resort, I decided to try something radical: I severely reduced the light: no window light (put up a blind) and only 4 hrs daily of 1 CFL slanted at an angle over the water surface.

Turns out, it worked! The Rotala and Vallisneria kept growing, the algae died, and the leaves of the crypts and Anubias shed their carpet of green fuzz algae. I then gradually lengthened the light period and changed the light to 1 bulb of cool white plus diffuse but very little window light. Some plants didn't survive the transition (the Marsilea and Ludwigia apparently need higher light and CO2), but others have thrived and are now dominating the tank (Vals and Rotala). The crypts look strong and healthy but being crypts, are not growing very fast.

So now, 6 months after setup, I finally have a relatively stable, low-mainenance, hardly-any-algae, true Walstad tank. Throughout all these developments, the water chemistry has been pretty stable and the fish healthy. No one has died although I don't see them for days at the time when they disappear into the jungle...

Here pics as it is right now: