Roots growing above substrate

[Mebbid]

I noticed that on some of my heavy root feeders like my amazon sword and especially my hammerleaf aponogeton that there are a bunch of roots growing up through the substrate. Does this mean that my sandbed isn't deep enough or is it a normal occurrence?

 

[calfishguy]

It's normal they are just trying to get nutriments from the water column instead or on top of the ones that are in the sand. Adding a few root tabs could perhaps keep them from surfacing.