Tropical Science Labs ATC99005 Liquid Gravel Vac Saltwater, 16-Ounce Tropical Science Labs Liquid Gravel Vac Saltwater Liquid Gravel Vac from Tropical Science Bio-labs utilizes the natural science of aquatic environmental chemistry Available in both saltwater and marine/reef formulations. Tropical Science Labs Liquid Gravel Vac Saltwater Liquid Gravel Vac from Tropical Science Bio-labs utilizes the natural science of aquatic environmental chemistry Available in both saltwater and marine/reef formulations Available in both saltwater and marine/reef formulations