Fluval Gravel Vac Multi-Substrate Cleaner. Take total control of the aquarium cleaning process with the Fluval GravelVac multi-substrate cleaner. Effectively traps dirt and debris Easy Start siphon for quick priming - starts with just a couple of pumps Thumb-operated flow regulator allows you to adjust speed as you clean Gravel guard prevents clogging Tube extension included for larger tanks and hard to reach areas Suitable for all substrates (sand, gravel, rock) For use in freshwater and saltwater aquariums Small - For Aquariums with a depth of 8-20 inches Large - For Aquariums with a depth of 8-24 inches