Substrate Additives

(also posted to rec.aquaria.freshwater.plants)

I have been looking around at the various alternative substrate additives.
I have come across a couple of products that I am not at all familiar with.
The first one is marketed by Sera and called "Flora Depot."  The second one
(I'm not sure who makes it) is called "Terralit."  Has anyone used these
products, and if so what can you say about them?

Andrew Roberts, in Toronto where it is _finally_ starting to warm up!