Circulate the water under gravel layer in order to reduce the corruption of gravel. The gravel bed provides tremendous surface area for Nitrobacteria and keeps your water crystal clear. The filter plate can be connected with air pump, filter pump, submersible power head and hang-on filter to increase the circulation and help with mechanical and chemical filtration. Adjustable lift tube can be modified at your desire height. Silence design tube head can reduce noise. Air stones will not stock or collapse. Works freshwater and saltwater tanks