I'm getting a small nano tank and want to use a very shallow layer of either white gravel or sand no thicker than a inch. I was wondering if anyone had any suggestions for plants that would do well in such a substrate and feed mostly from the water column.
I was thinking anubius or java ferns perhaps on a rock or wood?
A better view and much more based on observations: they get nutrients from both locations if they have roots, or....not. the sediment leaches nutrients either way.
So whether you want to believe one way or another really does not matter, if you add them to BOTH locations, then no matter who is correct, you have your bases covered. Replacing sediment is not something people tend to like to do on a tank that's up and running already really.
So do that.
Then you have a back up if you forget to dose the water, and you have a back up if you do not add ferts to the sediment or the sediment runs out of N etc.
This covers it all.