ok I notice that there is alot of postings on pebbles and stones being eaten by a poly. why is this? doesn't anyone know that the substrate needs to be sand? or EXTREMELY small pebbles so please take your gravel out OR cover it in my tank there is 4 inches+ of substrate eco complete on the bottom with 2 inches+ of sand on the top this way my poly does not eat anything he is not suposed to... share your thoughts...