Recently I have come across a few folks mentioning that substrate needs to be replaced every few year if not using an under gravel filter. I used to just focus on getting my substrate mature but now that I have some tanks that are three years old I am more noticing people talking about pockets in the substrate holding funky chemistry and other folks talking about overly compacted substrate impeding root growth. Would someone break it down for us? Shango _______________________________________________ GSAS-Member mailing list GSAS-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/gsas-member