Planted Tank Guru
Join Date: Nov 2009
Location: Missouri united states
Some folk's use a section of panthyhose filled with sand or gravel to help hold /create slopes and then cover these bundles with more sand,gravel.
Trumpet snail's can help sift through substrate to prevent hydrogen sulphide from building if one is worried about such thing's.
Plant's are capable of transporting oxygen to their root's ,plus sand would have to be on the order of four or five iches deep before I became worried about anaerobic problem becoming dangerous for critter's/fishes.
Some say hydrogen sulphide is rendered harmless once it escapes and makes contact with oxygen in the water.I tend to side with this view, for I have had sand tank's much deeper without any issues to fishes.
Nobody I know,or you know , fresh,or salt water ,could ever definitively point to hydrogen sulphide as cause for fish death's.
I fish small farm pond's,lakes, during the year with sand,mud bottom's, where nobody pokes or sift's the sand/mud yet fishes thrive .