Originally Posted by wildroseofky
Plants do better than if in gravel.
Substrate sifting fish and shrimp do better.
Easier to clean. Less waste gets trapped
You have to poke it to release trapped gas
You have to use a prefilter on the intake to keep it from hurting your filter
You have to be careful vacuuming it so you do not suck it up.
These are all good pros and cons. I will add one thing to the con list - silicates in some sand may lead to a diatom bloom, but this will usually clear up in a couple months on its own if it happens and it is harmless, just kind of ugly.
And no, you can't add it on top of your gravel. It will fall through the cracks in the gravel and eventually end up underneath the gravel.