not really, but its helpful. I have regular sand in my tank and my plants do quite well. In fact the banana plants have a well established root system in there.
I'm not saying that roots won't grow in sand but unless you have a substantial depth of sand then what are the roots going to bind to in order to anchor the plants? (That's assuming that the plants in question need to be rooted/anchored to something.) Wouldn't you need to help anchor them down with rocks, wood, etc.?
I'm not trying to start anything with you Mgamer. You are obviously much more experienced with this than I am. I'm more curious about how to make that work that anything else.
I think your plants will do just as well in sand as in plant substrate. if it's available look for 3m colorquarts. it's used in pools and is a lot cheaper than lfs sand.
same goes with gravel. just because you have sand doesnt mean it needs to be deeper then in gravel. i had stem plant in sand as little as 1/2 in sand. it stayed fine. not the best just what i had in there.
all my plants besides my new arrival and the java fern are well anchored in my sand bed. It wasn't hard either. if you look underneath the tank you can see the roots too.
My plants root way beter in sand than they ever did in gravel. I don't know how anyone can say otherwise. After using sand I would never go back to gravel. Much easier to clean and looks more natural IMO.