Join Date: Jun 2015
Location: Victoria, BC, Canada
You can just pat the surface down to even it out a bit, and then put the cap on.
We want to preserve micro-spaces. Folks later want to introduce this by using MTS (Malaysian trumpet snails which burrow into the top layers), and roots from plants also introduce microscopic air pockets. Just like angelcraze said.
It's just the big gaps that you want to avoid, because eventually the air releases and something else has to take its place, e.g. water, the substrate. If you fill the tank too fast with water, you could potentially get large air gaps as well.
Oops, I just saw that you are using Aquasoil. Do you mean ADA Aquasoil? No need to cap this stuff. It's light and would eventually work its way up and over your cap esp with uprooting and replanting.
Daisy Mae V
According to my husband, I have a habit of jumping right in!