Join Date: Jun 2008
Location: Orange County, CA
Well there are two potential issues. First I think it's a mistake to use topsoil unless you are going to mineralize it. People have had the most success consistently with Miracle Gro Organic Potting Mix when adding it straight to the tank.
Also I haven't ever used or seen pea gravel myself. However I have heard it may not be fine enough to use as a capping material. Perhaps others have done so though.