I use Elodea, java fern and java moss. Certainly not plants that develop complex root systems.
Recommending a thick layer of sand to a beginner is a risky businness in my opinion. Yes, with adequate maintenance, gas build up can be controlled and avoided, but you know what makes it easier? Avoiding the risk entirely...
I´m with Johnny, no substrate, nothing beats it. Mind you, if someone is dead set on using a substrate, instead of going for the complicated stuff, one should probably go for the easy options (at least until they gather up enough experience): Thin layer of sand, and plants that do well with such conditions.
How is it risky? What is so risky about keeping up with your part of the deal, maintenance of the tank?
If thats a risk then I am guilty of jeopardizing all my aquatic animals. You would wanna kill me if you saw how much sand I have in my Tanganyikan tanks
Java Moss and Fern do not grow in substrate they grow on rocks or plants, that's a null example.
How is 2" a thick substrate? look at any planted tank. I have loads of books including a huge collection of ones by Tikashi Ammano. The books include fish but its the same foundation. Keeping a balanced system to sustain aquatic life focusing on plants.
Bare bottom is the best but if aesthetics is a must sand is the way to go. If you have a small amount of
certain types of plants or
fake ones go with 1".
Let me edit this in.
Before I sound like a total sand Nazi allow me to give a great idea on substrate thats just as easy as bare bottom but as pleasing as sand.
Again, you wont get any root bound aquatic flora but some drift wood and rocks with some moss and some Anubas or Java Fern attached would work great.
Cover the bottom with aquarium safe black silicone. Before it dries dump some sand on it and press it in as hard as you can. Try to shake out the remaining sand that does not get stuck in and do a lighter cover pressing down firmly.
Allow it to harden and again dump out anything thats loose.
There you have a tank thats as pleasing to look at as sand, no paranoia of any gas, and just as easy to clean as a bare bottom.
It works great. I done it before and I got the tip off from members on this very forum.