I'm sorry, I didn't see these other replies until now. Thanks for the replies!
Gary, were you adding soil to an existing setup and reusing the seeded filter and old water?
darthmilmo, we finished the project last week and followed basically that method.
Although we went with 1" of soil with a ~1-1/2" small gravel cap.
The fish stayed in a container with the aquarium water, heater and airstone during the process. We initially filled the tank with fresh water, and left it with the filter running for a couple of hours. Then, we drained it again, planted and added back in the old aquarium water and fish.
So far, all is well. fyi, here's a before and after (I've encouraged my friend's daughter to start a journal here.
We were in the process of draining the tank when we thought it might be good to have a before shot for reference. The tank was lit with just one 15w gro-bulb that was at least a year old, w/ gravel substrate and infrequent fert dosing.
We replaced the solid top with a glass top, added an additional light for a total of 2- 15w gro-bulbs, and replaced the substrate w/ MGOCPM and a gravel cap. We reused all of her plants, plus added a lot more.
Some of the new inhabitants added, 3 panda cories, 2 blue rams, 3 neons to school with the existing lone neon, and one male dwarf gourami. This was immediately after acclimating them to their new home, so they're still hiding a bit.