oista soil for aquarium - 9 LA scientifically formulated substrate from natural soil sintered into a porous and granular structure with excellent filtering power. Sintered with organic acid; suitable fro shrimp, fresh water fish, and plants. Helps maintain stable, healthy, and clear water for long period of time. Lowers PH KH of the water; creates weak acid and soft water environment. Rapidly removes cloudiness and supports the development of aerobic bacteria.