Help your fresh- or saltwater aquarium stay clean and healthy with Microbe-Lift’s Gravel & Substrate Aquarium Cleaner! This natural formula works to rapidly break down toxic waste that collects on the bottom of your tank. Sludge and muck can be eliminated without disrupting your fish’s living environment， providing a gentle clean and stress-free tank. This organic cleaner is black and may cause slight discoloration in your water temporarily—but not to worry! The active ingredient works to make your aquarium crystal clear in 48-96 hours.