Planted Tank Guru
Join Date: Sep 2006
Location: Northern California
1) Depends on your fish or plants. Some do well in soft, some do well in hard.
2) I'm sure there is a limit of how many rocks you can put in, but to scape an aquarium, you probably won't hit that limit. There was a video where someone stacked 80+ pounds in a 10 gallon aquarium and then stepped into it too.