Planted Tank Enthusiast
Join Date: Apr 2011
Location: Pasadena, california
I think if you switch to soil the decomposing organics may cause an ammonia spike. On a transfered bacteria colony and an instant full bioload I would watch ammonia very carefully and be ready for some large water changes.
Usually, the transfered filter media should be adequate as long as you keep an eye on it, but with the soil, that may be equivolent to just adding a grip of fish to an established aquarium, so your mileage may vary.
If you're using soil and have the time, seed the new tank with soil in it as suggested above, and let it go through its cycle. That way you end up with enough bacteria in the tank to take care of the soil, and enough in the filter to take care of the fish. This also gives fine rooted plants time to establish in case you keep any catfish.
Flourite or other non organic, just allow the plants to root.