Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I have pool filter sand and Soil Master Select (or Turface) in most of my tanks, and have rarely seen (well, smelled) this problem. When the filters slow down I think this contributes. Less water movement above the substrate to remove the tiny trace of hydrogen sulfide and bring more O2 into the area starts a cycle that ends with anaerobic substrate.
Some of the substrate is pretty deep (4") in some tanks. I dig into it top plant stuff, but I think the MTS are at least somewhat responsible for reasonable well aerated substrate. Plants are not so dense in all the tanks to take care of it.
I have more often heard of problems with play sand. Finer material, and mixed particle sizes seem to pack together worse than the same-size material that is pool filter sand.