I have a 30 gal tank with sand on top of soil, I'd like to remove the sand and add a bit more soil, but while watching an aquascaping video the guy mentioned an ammonia spike with ADA soil, is this the case with all soils?
ADA Aquasoil Amazona is different from topsoil. It contains ammonia as manufactured, and it leaches some of it (new version) or lots of it (old version) for a few weeks. Topsoil can be lots of different things. Some may leach ammonia, some won't. If it is mineralized it shouldn't leach any ammonia because mineralizing converts the organic nitrogen (ammonia compounds) to inorganic nitrogen (nitrate compounds).