Has anyone tried this, is it basically "fancy" lava rock? Product says: Matrix™ is a high porosity biomedia that provides efficient biofiltration for the removal of nitrogenous waste. Matrix™ is a porous inorganic solid about 10 mm in diameter. Each liter of Matrix™ provides as much surface (<162 m) as 40 liters of plastic balls! Plastic bio-materials provide only external surface area, whereas Matrix™ provides internal macroporous surface area. These macropores are ideally sized for the support of nitrifying and denitrifying bacteria. This allows Matrix™, unlike other forms of biomedia, to remove nitrate along with ammonia and nitrite, simultaneously and in the same filter. Matrix™ is completely inert and will not breakdown. It need not be replaced.