Seachem Flourite Black Clay Gravel - Stable Porous Natural Planted Aquarium Substrate 15.4 lbsBrand: Seachem Color: RED Features: GRAVEL: Seachem Flourite Black is a specially fracted stable porous clay gravel for the natural planted aquarium. Its appearance is best suited to planted aquaria, but may be used in any freshwater aquarium environment. AQUARIUM BED: Gravel modifiers such as laterite are not necessary when using Seachem Flourite Black as this product is most effective when used alone as an integral substrate bed, but it may be mixed