I can't seem to get the water to clear. At first I thought it was the tannins from the driftwood, but the plants continue to get covered with silt that I brush off each week when I do a water change.
I would leave the tank alone for a few weeks at a time, but the water won't clear up.
Any help or ideas would be appreciated.
I performed a large water change. As much as I could remove without moving fish, and it helped a bit. But I feel like to only way to fix the water silt is to start over. Which will be horrible, because that is a lot of sand to replace (I used seachem flourite black sand as a cap, since I had it from the previous setup).
I wonder if your topsoil had colloidal clay in it. Colloidal clay is composed of particles so tiny that they never settle out of the water. Silt is definitely not your problem, because those particles are much larger and will settle out of the water in a matter of hours.
If you still have some of the topsoil, you could put a handful in a jar of water, shake it well, and see how long it takes for all the particles to settle out. If the water is still cloudy 24 to 48 hours later, you likely have colloidal clay.
A Diatom filter might take the particles out. A flocculent would also work. Focculents are substances that cause tiny particles to stick together so that they can settle or be filtered out. I've never needed a flocculent, so I don't know what types are safe for aquarium use, but Google might answer that question.
Over time, the biofilm in a mature aquarium acts as a flocculent, which is why you can disturb the soil layer in a Walstad tank without causing a muddy disaster. Time alone might cure your problem.
silty water NTP 
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